Aqueous fireproofing coating and its preparation process

Abstract

The application discloses a kind of water-based fireproof paint and preparation process thereof, and relates to functional coating technical field.The application uses fluorosilicon epoxy hybrid emulsion as base material, and comprises hydrophobic silica aerogel, composite microencapsulated flame retardant, composite bio-based charring agent, composite free radical trapping agent, reinforcing fiber and self-repairing microcapsule and other functional components.The water-based fireproof paint prepared by the application realizes efficient flame retardation and long-term protection through multiple synergistic mechanisms such as gas-phase free radical trapping, multi-layer heat-shielding shielding and self-repairing expanded carbon layer, and has excellent fire resistance, durability and mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of functional coatings technology, specifically to a water-based fire-retardant coating and its preparation process. Background Technology

[0002] Fire-retardant coatings, as an important type of special material, form a protective layer on the surface of a substrate, effectively delaying the transfer of heat to the substrate during a fire, thus buying time for escape and rescue. Among them, intumescent fire-retardant coatings have become a focus of research and application due to their high efficiency and good decorative properties. These coatings expand at high temperatures to form a porous foamed char layer, which has excellent heat insulation and oxygen barrier properties.

[0003] With increasingly stringent environmental regulations, water-based fire-retardant coatings have become a market trend due to their low volatile content and safety. However, existing water-based coatings still have many unresolved issues that restrict their application, such as: a single flame-retardant system, insufficient synergistic efficiency, an inability to simultaneously achieve physical and mechanical properties and fire resistance, poor durability, low long-term protection reliability, limited functionality, and a lack of self-adaptive and self-healing capabilities.

[0004] Therefore, there is an urgent need in this field for a new type of water-based fire-retardant coating that can not only build a highly efficient and synergistic multi-mode fire barrier, but also has excellent mechanical strength, long-term durability, and intelligent response capability to self-repair damage, thereby achieving more durable and reliable fire protection for the substrate. Summary of the Invention

[0005] The purpose of this invention is to provide a water-based fire-retardant coating and its preparation process to solve the problems mentioned in the background art.

[0006] In a first aspect, the present invention provides a water-based fire-retardant coating comprising, by weight, the following raw materials:

[0007] 30-36 parts of fluorosilicone epoxy hybrid emulsion;

[0008] 9-12 parts of hydrophobic silica aerogel;

[0009] Composite microencapsulated flame retardant: 12-15 parts;

[0010] 5-8 parts of composite bio-based charring agent;

[0011] 3-5 parts of complex free radical scavenger;

[0012] 1-2 parts of silane-modified cellulose nanofibers;

[0013] 2-3 parts of short-cut basalt fiber;

[0014] 1-2 parts of PCL fiber;

[0015] 2-3 portions of self-repairing microcapsules;

[0016] 0.5-1.5 parts of Grubb catalyst;

[0017] Nano CeO2 0.5-1 part;

[0018] 1-2 parts leveling agent

[0019] Dispersant 0.5-2 parts;

[0020] 1-3 parts of UV absorber;

[0021] 18-25 parts water.

[0022] As a preferred embodiment of the present invention, the preparation method of the fluorosilicone epoxy hybrid emulsion is as follows:

[0023] A1. Mix epoxy resin E-44, γ-glycidoxypropyltrimethoxysilane, methyl methacrylate, butyl acrylate, dodecafluoroheptyl methacrylate and acrylic acid and stir evenly. Add xylene, heat to 110-115℃, and add a xylene solution containing benzoyl peroxide dropwise over 1-2 hours. After the addition is complete, keep the mixture at 110-120℃ for 1-3 hours to obtain the prepolymer.

[0024] The mass ratio of epoxy resin E-44, γ-glycidoxypropyltrimethoxysilane, methyl methacrylate, butyl acrylate, dodecafluoroheptyl methacrylate, acrylic acid, benzoyl peroxide and xylene is 40:8:5:15:3:2:0.8:10.

[0025] A2. Cool the prepolymer obtained in step A1 to 60°C, add triethylamine, stir for 30 min, add deionized water, and pre-emulsify at 800 r / min for 15 min to obtain a pre-emulsion.

[0026] The molar ratio of triethylamine to epoxy groups is 0.8:1;

[0027] The mass ratio of deionized water to prepolymer is 1:2;

[0028] A3. Heat the pre-emulsion obtained in step A2 to 75°C, add ammonium persulfate aqueous solution, and react under nitrogen protection for 1-2 hours; then heat to 85°C and keep warm for 1 hour; cool the reaction solution to 65°C and let it stand under a vacuum of -0.095MPa for 12-14 hours to obtain fluorosilicone epoxy hybrid emulsion.

[0029] The mass ratio of ammonium persulfate to the total mass of the pre-emulsion is 1:50.

[0030] It should be noted that this fluorosilicone-epoxy hybrid emulsion is prepared by a combination of free radical copolymerization and epoxy modification. First, in step A1, the epoxy resin backbone is grafted with a silane coupling agent (γ-glycidoxypropyltrimethoxysilane) and a fluorinated acrylate monomer (dodecylfluoroheptyl methacrylate) to form a prepolymer possessing the toughness of epoxy groups, the flexibility of organosilicon, and the hydrophobicity of organofluorine. In steps A2 and A3, the carboxyl groups introduced by acrylic acid are neutralized by triethylamine to form a salt, imparting water dispersibility to the prepolymer. Its structure is further stabilized by emulsion polymerization initiated by ammonium persulfate. The resulting fluorosilicone-epoxy hybrid emulsion, after film formation, forms a dense and robust paint film. The organosilicon segments enhance the heat resistance and flexibility of the paint film, while the fluorinated segments migrating to the film surface provide excellent hydrophobicity and stain resistance. Fluorosilicone epoxy hybrid emulsions, as film-forming substances in coatings, provide a stable, durable, and weather-resistant bonding substrate for all functional fillers.

[0031] As a preferred embodiment of the present invention, the preparation method of the hydrophobic silica aerogel is as follows:

[0032] B1. At 30℃, tetraethyl orthosilicate, anhydrous ethanol and deionized water are mixed evenly, and the pH is adjusted to 2-3 with 0.5mol / L hydrochloric acid. The mixture is then hydrolyzed for 1 hour with stirring at 300r / min to obtain a transparent sol.

[0033] The mass ratio of tetraethyl orthosilicate, anhydrous ethanol, and deionized water is 3:7:1.

[0034] B2. Add ammonia to adjust the pH of the transparent sol obtained in step B1 to 7-8, add hexadecyltrimethylammonium bromide, and let it stand at 40°C for 4 hours to gel, to obtain a wet gel. Soak the wet gel in anhydrous ethanol at 50°C for 24 hours to age, changing the ethanol 3 times during the process.

[0035] The mass ratio of hexadecyltrimethylammonium bromide to tetraethyl orthosilicate is 1:(18-22);

[0036] B3. The aged gel obtained in step B2 is immersed in a hexane solution containing heptadecanodecyltrimethoxysilane with a mass fraction of 5-20%, reacted at 60°C for 6 hours, dried at 80°C for 4 hours, vacuum dried at 150°C for 2 hours, and ground through a 200-mesh sieve to obtain hydrophobic silica aerogel.

[0037] The mass ratio of the gel to the hexane solution of heptadecafluorodecyltrimethoxysilane is 1:(8-12).

[0038] It should be noted that this hydrophobic silica aerogel was prepared via a sol-gel method combined with surface hydrophobic modification. Under acidic conditions, tetraethyl orthosilicate hydrolyzes to generate silanol groups, which condense under alkaline conditions to form a three-dimensional nano-network structure of silica wet gel. The addition of hexadecyltrimethylammonium bromide helps to regulate the gel pore structure. The long-chain fluoroalkyl group in heptadecafluorodecyltrimethoxysilane replaces the silanol groups on the surface of the gel skeleton through a silanol condensation reaction, achieving hydrophobic modification with extremely low surface energy. The resulting hydrophobic silica aerogel powder has high porosity and low thermal conductivity. When dispersed in coatings, it can construct a nanoscale porous heat insulation layer within the paint film, effectively blocking heat transfer to the substrate. Its hydrophobic properties not only improve the water resistance and durability of the coating, but also delay the damage of water vapor to the expanding char layer in the early stages of combustion, synergistically enhancing the heat insulation effect with the composite microencapsulated flame retardant.

[0039] As a preferred embodiment of the present invention, the preparation method of the composite microencapsulated flame retardant is as follows:

[0040] C1. Polycaprolactone was dissolved in dichloromethane to obtain a PCL solution; ammonium polyphosphate, pentaerythritol and melamine were mixed evenly and ground through a 200-mesh sieve to obtain a flame retardant mixture; the flame retardant mixture was dispersed in deionized water, sodium dodecyl sulfate was added, and the mixture was sheared at 8000-12000 r / min for 10-15 min to obtain a dispersion; the dispersion was added dropwise to the PCL solution, sheared at 15-20 min, stirred in a 40℃ water bath for 2 h, centrifuged, washed 3 times with deionized water, and dried at 60℃ for 12 h to obtain PCL flame retardant microspheres;

[0041] The mass ratio of polycaprolactone to dichloromethane is 1:(4-10);

[0042] The mass ratio of ammonium polyphosphate, pentaerythritol, melamine, deionized water, and sodium dodecyl sulfate is 40:16:10:200:1.

[0043] The mass ratio of the PCL solution to the dispersion is (4-6):1;

[0044] C2. Disperse the PCL flame-retardant microspheres obtained in step C1 in deionized water and sonicate for 30-40 min to obtain a suspension; dissolve magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water to obtain a mixed salt solution; add the mixed salt solution dropwise to the suspension, adjust the pH to 9.3-9.7, stir in a 60℃ water bath for 6 h, centrifuge, wash until neutral, and dry to obtain crude capsules;

[0045] The mass ratio of the PCL flame-retardant microspheres to deionized water is 1:(12-18);

[0046] The mass ratio of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and deionized water is 7:3.6:100;

[0047] The mass ratio of the suspension to the mixed salt solution is 3:1;

[0048] C3. Disperse the crude capsules obtained in step C2 in an aqueous sodium borate solution, stir at 80°C for 2 hours, centrifuge, wash three times with deionized water, and dry at 60°C for 12 hours to obtain a composite microencapsulated flame retardant.

[0049] The mass ratio of the crude product capsules to the sodium borate aqueous solution is 1:(8-12);

[0050] The sodium borate aqueous solution has a mass fraction of 0.5-1.5%.

[0051] It should be noted that in step C1, the flame retardant components consisting of ammonium polyphosphate, pentaerythritol, and melamine are coated with polycaprolactone using a solvent evaporation method to form primary microspheres, which effectively improves the hygroscopicity of ammonium polyphosphate and achieves preliminary isolation and slow release of the flame retardant components; in step C2, a magnesium-aluminum layered bimetallic hydroxide shell is grown in situ on the surface of the PCL microspheres by a co-precipitation method; and in step C3, borate is introduced into the LDH interlayer through ion exchange. Multi-level core-shell structured composite microencapsulated flame retardants can achieve the orderly release and synergistic effect of flame retardant components in time and space: In the early stage of a fire, the outer LDH shell decomposes upon heating, absorbing a large amount of heat and releasing water vapor and carbon dioxide, diluting the concentration of combustible gases and oxygen; the inner PCL coating layer melts and releases flame retardant components (ammonium polyphosphate, pentaerythritol, and melamine), which undergo esterification, char formation, and foaming reactions to form the main framework of the expanded char layer; at the same time, the borate ions exchanged from the LDH layer can vitrify at a lower temperature, synergistically with the char-forming agent to further improve the anti-dripping and continuity of the char layer, thereby significantly improving the expansion char formation efficiency, char layer quality, heat insulation effect, and sustained flame retardant time of the coating.

[0052] As a preferred embodiment of the present invention, the preparation method of the composite bio-based charring agent is as follows:

[0053] D1. Alkali lignin, 2,3-epoxypropyltrimethylammonium chloride and deionized water were mixed and stirred at 60°C for 6 hours. The pH was adjusted to 10-11, centrifuged, washed with deionized water until neutral, and dried at 60°C for 12 hours to obtain quaternized lignin.

[0054] The mass ratio of the alkali lignin, 2,3-epoxypropyltrimethylammonium chloride, and deionized water is 6:1.6:30.

[0055] D2. Place rice husk powder in a muffle furnace and heat it to 600℃ at 3℃ / min under nitrogen protection, and keep it at that temperature for 2h. After natural cooling, soak it in a 2mol / L HNO3 solution for 12h, wash it with deionized water until neutral, and vacuum dry it at 60℃ for 12h to obtain porous biochar.

[0056] The mass ratio of rice husk powder to HNO3 solution is 1:5;

[0057] D3. Mix the quaternized lignin obtained in step D1, the porous biochar obtained in step D2, and sodium alginate, add deionized water, stir at 80°C for 1 hour, and spray dry to obtain a composite bio-based char agent.

[0058] The inlet temperature of the spray drying operation is 180-200℃, and the outlet temperature is 85-95℃;

[0059] The mass ratio of the quaternized lignin, porous biochar, sodium alginate, and deionized water is 3:5:2:100.

[0060] It should be noted that this composite bio-based charring agent integrates the functions of three biomass materials through a physicochemical composite method. Quaternized lignin introduces nitrogen and, due to its cationic properties, is more compatible with other components in the coating. When heated, it promotes charring and releases inert gases. Porous biochar itself is a stable carbonaceous skeleton; its rich pore structure can adsorb gaseous pyrolysis products, delay combustion, and serve as a supporting skeleton. Acid treatment removes impurities and increases its surface functional groups. Sodium alginate, as a biopolymer, is rich in carboxyl groups and can rapidly dehydrate and crosslink to form an initial char layer network when heated. After the three are combined, during combustion, sodium alginate and lignin act as char sources to form a foamed char layer, while porous biochar acts as a char skeleton embedded within it, effectively enhancing the strength, continuity, and anti-collapse ability of the expanded char layer. This produces a significant synergistic effect with the acid source (ammonium polyphosphate) and gas source (melamine) released by the composite microencapsulated flame retardant.

[0061] As a preferred embodiment of the present invention, the preparation method of the composite free radical scavenger is as follows:

[0062] E1. Mix citric acid, urea and L-cysteine ​​evenly, heat to 190-200℃ at a rate of 5℃ / min under a nitrogen atmosphere, keep warm for 2-3h, dissolve the obtained carbon quantum dot precursor in deionized water, and ultrasonically disperse for 30min to obtain a carbon quantum dot precursor solution.

[0063] The mass ratio of citric acid, urea and L-cysteine ​​is 5:4:1;

[0064] The mass ratio of the carbon quantum dot precursor to deionized water is 1:(8-12);

[0065] E2. Add ammonium tetrathiomolybdate, boric acid and ascorbic acid to the carbon quantum dot precursor solution, heat to 170-180℃ under nitrogen atmosphere, react for 12-14h, cool naturally to room temperature, centrifuge, wash 3 times with deionized water, dry at 60℃ for 12-24h, grind through a 200-mesh sieve, and the composite free radical scavenger is obtained.

[0066] The mass ratio of the ammonium tetrathiomolybdate, boric acid, ascorbic acid, and carbon quantum dot precursor solution is 1:0.4:0.1:10.

[0067] It should be noted that in the E1 step, citric acid, urea and L-cysteine ​​undergo pyrolysis under an inert atmosphere, and through intermolecular condensation, carbonization and heteroatom doping, nitrogen and sulfur co-doped carbon quantum dots (CQDs) are generated. This carbon quantum dot precursor possesses excellent water dispersibility, abundant surface defects, and functional groups, providing nucleation sites for subsequent reactions. Furthermore, the thiol groups introduced from L-cysteine ​​facilitate coordination with the molybdenum source. In the E2 step, using the carbon quantum dot precursor solution as the reaction matrix, ammonium tetrathiomolybdate, boric acid, and ascorbic acid are added. Under solvothermal conditions, ascorbic acid acts as a reducing agent, promoting the decomposition of ammonium tetrathiomolybdate and its in-situ reduction on the carbon quantum dot surface, guiding the growth of molybdenum disulfide nanosheets. Simultaneously, boron atoms released by the thermal decomposition of boric acid are incorporated into the MoS2 lattice, forming boron-doped MoS2 (B-MoS2). Boron doping (substituting sulfur sites) introduces holes, reducing the MoS2 band gap and enhancing electron cloud density redistribution (boron doping reduces the electron density of surrounding sulfur atoms), thus increasing the activity of its edge unsaturated sulfur atoms. The prepared composite radical scavenger is a heterostructure coupling B-MoS2 nanosheets and carbon quantum dots (CQDs). The CQDs act as a dispersion carrier to inhibit MoS2 aggregation, and their surface functional groups can directly adsorb gaseous radicals. Furthermore, the heterostructure interface between CQDs and B-MoS2 promotes interfacial charge transfer, generating an electronic synergistic effect that enhances the capture and recombination efficiency of high-energy H· and OH· radicals during combustion. In the combustion gas phase, highly active edge sulfur atoms react with radicals on the surface to form stable intermediates, which synergistically quench radicals through heterostructure interface charge transfer, interrupting the chain reaction. Simultaneously, the semiconductor properties of MoS2 and the electronic conductivity of CQDs synergistically enhance the catalytic activity for radical quenching. The composite radical scavenger exerts its gas-phase flame-retardant effect through these multiple mechanisms, synergistically constructing a highly efficient fire barrier with the barrier layer formed by other components in the condensed phase of the coating.

[0068] As a preferred embodiment of the present invention, the silane-modified cellulose nanofibers are cellulose nanofibers obtained through pretreatment, wherein the length of the cellulose nanofibers is 200-500 nm, the diameter is 10-30 nm, and the aspect ratio is (10-30):1.

[0069] As a preferred embodiment of the present invention, the chopped basalt fiber has a length of 1-3 mm, a fiber diameter of 10-18 μm, a monofilament tensile strength of not less than 3000 MPa, and a heat resistance temperature of not less than 600℃.

[0070] As a preferred embodiment of the present invention, the PCL fiber has a length of 2-4 mm and a fiber diameter of 15-25 μm.

[0071] As a preferred embodiment of the present invention, the method for preparing the self-healing microcapsules is as follows:

[0072] F1. Mix dicyclopentadiene, ethyl cellulose and Span-80, and stir to dissolve at 40°C to obtain the oil phase;

[0073] The mass ratio of dicyclopentadiene, ethyl cellulose and Span-80 is 125:10:4;

[0074] F2. Dissolve gelatin and gum arabic in deionized water and stir at 50°C to dissolve. Adjust the pH to 4.5 with acetic acid solution to obtain an aqueous phase. Add the oil phase obtained in step F1 to the aqueous phase and emulsify at high speed of 800-1200 r / min for 10 min to form an oil-in-water emulsion.

[0075] The mass ratio of gelatin, gum arabic, and deionized water is 1:1:(45-55); the mass ratio of oil phase to water phase is 1:(5-7);

[0076] F3. Cool the oil-in-water emulsion obtained in step F2 to 45°C, adjust the pH to 9.0 with NaOH solution, add glutaraldehyde solution, and stir for 2 hours; then add hydrochloric acid solution to adjust the pH to 3.0, and continue the reaction for 1 hour; dilute the reaction solution with deionized water, centrifuge, wash 3 times with deionized water, and vacuum dry at 40°C for 12 hours to obtain self-healing microcapsules.

[0077] The glutaraldehyde solution has a mass fraction of 50%, and the mass ratio of glutaraldehyde to the oil-in-water emulsion is 3:50.

[0078] It should be noted that the self-healing microcapsules are prepared via a composite coagulation method. Utilizing the opposite charge properties of gelatin and gum arabic at a specific pH, they are alternately deposited on the surface of oil droplets (F1 oil phase) to form a composite wall material. Glutaraldehyde, acting as a crosslinking agent, reacts with the amino groups of gelatin in a Schiff base reaction, enhancing the mechanical strength and chemical stability of the wall material. When microcracks develop in the coating, the crack propagation stress destroys the self-healing microcapsules, releasing a liquid dicyclopentadiene core. Upon contact with the Grubb catalyst in the formulation system, dicyclopentadiene undergoes a ring-opening metathesis polymerization reaction, generating a crosslinked polymer, thus achieving self-repair of the microcracks. This effectively restores the physical barrier function of the coating, delays the impact of cracks on the substrate under fire conditions, and improves the long-term protective performance and fire resistance integrity of the coating.

[0079] As a preferred embodiment of the present invention, the Grubb catalyst is a third-generation Grubb catalyst that has undergone microencapsulation treatment. The third-generation Grubb catalyst is (1,3-bis(2,4,6-trimethylphenyl)-2-imidazolinyl)dichloro(o-isopropoxybenzyl)ruthenium.

[0080] As a preferred embodiment of the present invention, the leveling agent is polyether-modified polydimethylsiloxane.

[0081] As a preferred embodiment of the present invention, the dispersant is obtained by mixing sodium polyacrylate and polymaleic anhydride in a mass ratio of 2:1.

[0082] As a preferred embodiment of the present invention, the ultraviolet absorber is one or more of 2-hydroxy-4-methoxybenzophenone and triazine ultraviolet absorbers.

[0083] A second aspect of the present invention provides a process for preparing a water-based fire-retardant coating, comprising the following steps:

[0084] S1. Weigh the raw materials according to the weight parts, add the fluorosilicone epoxy hybrid emulsion into the dispersion vessel, and stir at a low speed of 300-400r / min.

[0085] S2. Premix the leveling agent, dispersant, UV absorber and 30-50% of the total water volume with water, stir until uniform, and then slowly add to the dispersion vessel in step S1, and mix evenly with the base emulsion.

[0086] S3. While stirring at 400-600 r / min, add hydrophobic silica aerogel, composite microencapsulated flame retardant, composite bio-based charring agent, composite free radical scavenger and nano CeO2 to the dispersion vessel in sequence, increase the stirring speed to 1200-1500 r / min and stir for 20-30 min.

[0087] S4. Reduce the stirring speed to 300-400 r / min, add silane-modified cellulose nanofibers, short-cut basalt fibers and PCL fibers in sequence, and stir for 10-15 min to ensure that the fibers are evenly dispersed without obvious entanglement;

[0088] S5. Maintain low-speed stirring, add self-healing microcapsules and Grubb catalyst in sequence, stir for 15-20 minutes to ensure uniform distribution in the whole system;

[0089] S6. Use the remaining water to adjust the viscosity of the coating to 1500-2500 mPa·s, stir at 100-200 r / min for 5-10 min, and discharge to obtain the water-based fireproof coating.

[0090] Compared with the prior art, the present invention has the following beneficial effects:

[0091] (1) This invention combines three mechanisms—gas-phase flame retardancy, condensed-phase flame retardancy, and high-efficiency thermal insulation—to construct a multi-level synergistic fire protection system. Upon heating, the composite microencapsulated flame retardant orderly releases acid, gas, and carbon sources, and synergistically with the metal oxides generated by the decomposition of borate-intercalated LDH to catalyze the formation of a dense, expanded char layer with high strength and good thermal insulation performance. At the same time, the composite free radical scavenger efficiently quenches the free radicals in the combustion chain reaction in the gas phase. The hydrophobic silica aerogel constructs a nanoscale thermal insulation barrier inside and at the bottom of the char layer, jointly building a gas-phase / condensed-phase / physical thermal insulation fire protection barrier, significantly improving the fire resistance limit and smoke suppression performance of the coating.

[0092] (2) This invention, through the design of the matrix resin and functional fillers, ensures both fire resistance and the physical and mechanical properties and long-term durability of the coating. The fluorosilicone epoxy hybrid emulsion provides a strong, dense, hydrophobic, and weather-resistant bonding substrate for the coating; silane-modified cellulose nanofibers, chopped basalt fibers, and PCL fibers form a multi-level reinforcing network from nanometer to micrometer scale in the coating, effectively improving the coating's toughness, crack resistance, and overall strength. Furthermore, the introduction of UV absorbers and nano-CeO2 enhances the coating's resistance to UV aging, ensuring its long-term functional stability in outdoor environments.

[0093] (3) This invention applies a dicyclopentadiene / Grubb catalyst system to water-based fire-retardant coatings, introducing a self-healing function to improve coating reliability and service life. When the coating develops microcracks due to external forces, the crack tip punctures the self-healing microcapsules and exposes the Grubb catalyst. The released repair monomers undergo ring-opening metathesis polymerization under the action of the catalyst, achieving autonomous repair of the microcracks. This can promptly repair early damage to the coating during transportation, construction, and use, effectively preventing premature exposure of the substrate and attenuation of fire resistance caused by crack propagation, and improving the long-term protective reliability and service life of the fire-retardant coating. Detailed Implementation

[0094] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0095] Preparation Example 1

[0096] The preparation method of fluorosilicone epoxy hybrid emulsion is as follows:

[0097] A1. By weight, 200 parts of epoxy resin E-44, 40 parts of γ-glycidyl etheroxypropyltrimethoxysilane, 25 parts of methyl methacrylate, 75 parts of butyl acrylate, 15 parts of dodecafluoroheptyl methacrylate and 10 parts of acrylic acid are mixed and stirred for 1 hour. 14 parts of xylene are added, the temperature is raised to 110°C, and 40 parts of xylene solution containing 4 parts of benzoyl peroxide are added dropwise over 1 hour. After the addition is complete, the mixture is kept at 115°C for 2 hours to obtain the prepolymer.

[0098] A2. Cool 100 parts of the prepolymer obtained in step A1 to 60°C, add 8.7 parts of triethylamine, stir for 30 min, add deionized water, and pre-emulsify at 800 r / min for 15 min to obtain a pre-emulsion.

[0099] The molar ratio of triethylamine to epoxy groups is 0.8:1;

[0100] The mass ratio of deionized water to prepolymer is 1:2;

[0101] A3. Heat 50 parts of the pre-emulsion obtained in step A2 to 75°C, add 100 parts of ammonium persulfate aqueous solution with a mass fraction of 1%, and react for 2 hours under nitrogen protection; then heat to 85°C and keep warm for 1 hour; cool the reaction solution to 65°C and let it stand for 14 hours under a vacuum of -0.095 MPa to obtain a fluorosilicone epoxy hybrid emulsion.

[0102] Preparation Example 2

[0103] The preparation method of hydrophobic silica aerogel is as follows:

[0104] B1. By weight, at 30°C, mix 60 parts of tetraethyl orthosilicate, 140 parts of anhydrous ethanol, and 20 parts of deionized water evenly. Adjust the pH to 3 with 0.5 mol / L hydrochloric acid and hydrolyze for 1 hour with stirring at 300 r / min to obtain a transparent sol. Add ammonia to adjust the pH of the transparent sol to 7.5, add 3 parts of hexadecyltrimethylammonium bromide, and let it stand at 40°C for 4 hours to gel, obtaining a wet gel. Soak the wet gel in anhydrous ethanol at 50°C for 24 hours to age, changing the ethanol 3 times during the process.

[0105] B2. Soak 10 parts of the aged gel obtained in step B2 in a hexane solution containing 100 parts of heptadecanofluorodecyltrimethoxysilane at a mass fraction of 10%, react at 60°C for 6 hours, dry at 80°C for 4 hours, vacuum dry at 150°C for 2 hours, grind through a 200-mesh sieve to obtain hydrophobic silica aerogel.

[0106] Preparation Example 3

[0107] The preparation method of the composite microencapsulated flame retardant is as follows:

[0108] C1. By weight, 100 parts of polycaprolactone were dissolved in 400 parts of dichloromethane to obtain a PCL solution; 20 parts of ammonium polyphosphate, 8 parts of pentaerythritol, and 5 parts of melamine were mixed evenly and ground through a 200-mesh sieve to obtain a flame retardant mixture; the flame retardant mixture was dispersed in 100 parts of deionized water, and 1 part of sodium dodecyl sulfate was added; the mixture was sheared at 10,000 r / min for 15 min to obtain a dispersion; 100 parts of the dispersion were added dropwise to 500 parts of PCL solution, sheared at high speed for 20 min, stirred in a 40℃ water bath for 2 h, centrifuged, washed 3 times with deionized water, and dried at 60℃ for 12 h to obtain PCL flame retardant microspheres.

[0109] C2. Disperse 10 parts of the PCL flame-retardant microspheres obtained in step C1 in 150 parts of deionized water, and sonicate for 40 min to obtain a suspension; add 7 parts of magnesium nitrate hexahydrate and 3.6 parts of aluminum nitrate nonahydrate to 100 parts of deionized water to obtain a mixed salt solution; add 50 parts of the mixed salt solution dropwise to 150 parts of the suspension, adjust the pH to 9.5, stir in a 60℃ water bath for 6 h, centrifuge, wash until neutral, and dry to obtain crude capsules;

[0110] C3. Disperse 1 part of the crude capsule obtained in step C2 in 10 parts of sodium borate aqueous solution with a mass fraction of 1%, stir and react at 80°C for 2 hours, centrifuge, wash 3 times with deionized water, and dry at 60°C for 12 hours to obtain the composite microencapsulated flame retardant.

[0111] Preparation Example 4

[0112] The preparation method of the composite bio-based charring agent is as follows:

[0113] D1. By weight, 6 parts of alkali lignin, 1.6 parts of 2,3-epoxypropyltrimethylammonium chloride and 30 parts of deionized water were mixed and stirred at 60°C for 6 hours. The pH was adjusted to 10.5, centrifuged, washed with deionized water until neutral, and dried at 60°C for 12 hours to obtain quaternized lignin.

[0114] D2. Place 10 parts of rice husk powder in a muffle furnace, heat it to 600℃ at 3℃ / min under nitrogen protection, and keep it at that temperature for 2h. After natural cooling, soak it in 50 parts of 2mol / L HNO3 solution for 12h, wash it with deionized water until neutral, and vacuum dry it at 60℃ for 12h to obtain porous biochar.

[0115] D3. Mix 3 parts of quaternized lignin obtained in step D1, 5 parts of porous biochar obtained in step D2, and 2 parts of sodium alginate, add 100 parts of deionized water, stir at 80°C for 1 hour, spray dry at an inlet temperature of 180°C and an outlet temperature of 90°C to obtain a composite bio-based char-forming agent.

[0116] Preparation Example 5

[0117] The preparation method of the composite free radical scavenger is as follows:

[0118] E1. By weight, mix 0.5 parts citric acid, 0.4 parts urea and 0.1 parts L-cysteine ​​evenly, heat to 190°C at a rate of 5°C / min under a nitrogen atmosphere, and keep warm for 2 hours. Dissolve 1 part of the obtained carbon quantum dot precursor in 10 parts deionized water and sonicate for 30 minutes to obtain a carbon quantum dot precursor solution.

[0119] E2. Add 1 part ammonium tetrathiomolybdate, 0.4 parts boric acid and 0.1 parts ascorbic acid to 10 parts carbon quantum dot precursor solution, heat to 170℃ under nitrogen atmosphere, react for 14h, cool naturally to room temperature, centrifuge, wash 3 times with deionized water, dry at 60℃ for 18h, grind through a 200-mesh sieve, and the composite free radical scavenger is obtained.

[0120] Preparation Example 6

[0121] The preparation method of self-healing microcapsules is as follows:

[0122] F1. By weight, 12.5 parts of dicyclopentadiene, 1 part of ethyl cellulose and 0.4 parts of Span-80 are mixed and stirred at 40°C to dissolve, thus obtaining the oil phase;

[0123] F2. Dissolve 1 part gelatin and 1 part gum arabic in 50 parts deionized water, stir and dissolve at 50°C, adjust the pH to 4.5 with acetic acid solution to obtain an aqueous phase; add 8 parts of the oil phase obtained in step F1 to the aqueous phase, and emulsify at high speed of 1000 r / min for 10 min to form an oil-in-water emulsion.

[0124] F3. Cool 50 parts of the oil-in-water emulsion obtained in step F2 to 45°C, adjust the pH to 9.0 with NaOH solution, add 3 parts of 50% glutaraldehyde solution, and stir for 2 hours; then add hydrochloric acid solution to adjust the pH to 3.0 and continue the reaction for 1 hour; dilute the reaction solution with deionized water, centrifuge, wash 3 times with deionized water, and vacuum dry at 40°C for 12 hours to obtain self-healing microcapsules.

[0125] Preparation Example 7

[0126] The preparation method of silane-modified cellulose nanocrystals is as follows:

[0127] By weight, 20 parts of cellulose nanofibers were dispersed in 200 parts of 64% sulfuric acid solution, stirred at 45°C for 45 min, and the reaction was terminated by adding 1000 parts of ice water. After centrifugation, the mixture was washed with deionized water until neutral. The obtained cellulose nanofibers were dispersed in 100 parts of deionized water, and 3 parts of 3-aminopropyltriethoxysilane (KH-550 silane coupling agent) were added. The mixture was stirred at 60°C for 4 h, centrifuged, washed three times with ethanol, and dried at 60°C for 12 h to obtain silane-modified cellulose nanofibers.

[0128] The cellulose nanocrystals have an average length of 350 nm, an average diameter of 20 nm, and an average aspect ratio of 20:1.

[0129] Preparation Example 8

[0130] The dispersant is prepared as follows:

[0131] The sodium polyacrylate and polymaleic anhydride are mixed in a mass ratio of 2:1 to obtain the product.

[0132] Preparation Example 9

[0133] The preparation method of microencapsulated third-generation Grubb catalyst is as follows:

[0134] By weight, 1 part of third-generation Grubb catalyst was dissolved in 20 parts of anhydrous dichloromethane to obtain an oil phase solution; 2 parts of hydrophobic fumed silica were dispersed in 100 parts of deionized water, and 0.5 parts of Span-80 were added. The mixture was stirred at 400 rpm for 30 min at 40°C to obtain an aqueous phase dispersion; the oil phase solution obtained in step G1 was added dropwise to the aqueous phase dispersion obtained in step G2 while stirring at 600 rpm. After the addition was complete, the stirring speed was increased to 600 rpm. High-speed shear emulsification at 0 r / min for 10 min was used to form a stable oil-in-water primary emulsion. A mixed solution containing 10 parts tetraethyl orthosilicate, 5 parts methyltriethoxysilane, and 30 parts anhydrous ethanol was added dropwise under stirring at 300 r / min in a 40℃ water bath for 1 h. After addition, the pH of the system was adjusted to 6.5, and the reaction was continued at 40℃ for 6 h. After centrifugation, the emulsion was washed three times each with anhydrous ethanol and deionized water, dried at 40℃ for 12 h, and ground through a 200-mesh sieve to obtain the microencapsulated Grubb catalyst. Example

[0135] A water-based fire-retardant coating comprises the following raw materials in parts by weight:

[0136] 33 parts of fluorosilicone epoxy hybrid emulsion;

[0137] 10.5 parts of hydrophobic silica aerogel;

[0138] Composite microencapsulated flame retardant: 13.5 parts;

[0139] 6.5 parts of composite bio-based charring agent;

[0140] Four parts of a complex free radical scavenger;

[0141] 1.5 parts of silane-modified cellulose nanocrystals;

[0142] 2.5 parts of short-cut basalt fiber;

[0143] 1.5 parts PCL fiber;

[0144] 2.5 portions of self-healing microcapsules;

[0145] One part of microencapsulated third-generation Grubb catalyst;

[0146] 0.8 parts of nano CeO2;

[0147] 1.5 parts of polyether-modified polydimethylsiloxane

[0148] 1.2 parts dispersant;

[0149] Two parts of UV-1577 ultraviolet absorber;

[0150] 20 parts water.

[0151] A preparation process for a water-based fire-retardant coating includes the following steps:

[0152] S1. Weigh the raw materials according to the weight parts, add the fluorosilicone epoxy hybrid emulsion into the dispersion vessel, and stir at a low speed of 300r / min.

[0153] S2. Premix the polyether-modified polydimethylsiloxane, dispersant, UV-1577 ultraviolet absorber with 40% of the total water volume, stir until uniform, and then slowly add it to the dispersion vessel of step S1 to mix evenly with the base emulsion.

[0154] S3. Under stirring at 500 r / min, add hydrophobic silica aerogel, composite microencapsulated flame retardant, composite bio-based charring agent, composite free radical scavenger and nano CeO2 to the dispersion vessel in sequence, increase the stirring speed to 1200 r / min and stir for 30 min.

[0155] S4. Reduce the stirring speed to 300 r / min, add silane-modified cellulose nanocrystals, short-cut basalt fibers and PCL fibers in sequence, and stir for 10 min.

[0156] S5. Maintain low-speed stirring, add self-healing microcapsules and microencapsulated third-generation Grubb catalyst in sequence, stir for 20 minutes to ensure that they are evenly distributed in the whole system.

[0157] S6. Use the remaining water to adjust the viscosity of the coating to 2000 mPa·s, stir at 150 r / min for 8 min, and discharge to obtain the water-based fireproof coating.

[0158] In this embodiment, some of the raw materials used are the same as those obtained in Preparation Examples 1-9, and the other examples are the same. Example

[0159] A water-based fire-retardant coating comprises the following raw materials in parts by weight:

[0160] 30 parts of fluorosilicone epoxy hybrid emulsion;

[0161] Nine portions of hydrophobic silica aerogel;

[0162] Composite microencapsulated flame retardant: 12 parts;

[0163] 5 parts of composite bio-based charring agent;

[0164] Three parts of a complex free radical scavenger;

[0165] One part of silane-modified cellulose nanofibers;

[0166] Two portions of short-cut basalt fibers;

[0167] 1 part PCL fiber;

[0168] Two doses of self-repairing microcapsules;

[0169] 0.5 parts of microencapsulated third-generation Grubb catalyst;

[0170] 0.5 parts of nano CeO2;

[0171] 1 part of polyether-modified polydimethylsiloxane

[0172] 0.5 parts of dispersant;

[0173] One part of UV-1577 ultraviolet absorber;

[0174] 19 portions of water.

[0175] A preparation process for a water-based fire-retardant coating includes the following steps:

[0176] S1. Weigh the raw materials according to the weight parts, add the fluorosilicone epoxy hybrid emulsion into the dispersion vessel, and stir at a low speed of 300r / min.

[0177] S2. Premix the polyether-modified polydimethylsiloxane, dispersant, UV-1577 ultraviolet absorber with 40% of the total water volume, stir until uniform, and then slowly add it to the dispersion vessel of step S1 to mix evenly with the base emulsion.

[0178] S3. Under stirring at 500 r / min, add hydrophobic silica aerogel, composite microencapsulated flame retardant, composite bio-based charring agent, composite free radical scavenger and nano CeO2 to the dispersion vessel in sequence, increase the stirring speed to 1200 r / min and stir for 30 min.

[0179] S4. Reduce the stirring speed to 300 r / min, add silane-modified cellulose nanocrystals, short-cut basalt fibers and PCL fibers in sequence, and stir for 10 min.

[0180] S5. Maintain low-speed stirring, add self-healing microcapsules and microencapsulated third-generation Grubb catalyst in sequence, stir for 20 minutes to ensure that they are evenly distributed in the whole system.

[0181] S6. Use the remaining water to adjust the viscosity of the coating to 2000 mPa·s, stir at 150 r / min for 8 min, and discharge to obtain the water-based fireproof coating.

[0182] In this embodiment, some of the raw materials used are the same as those obtained in Preparation Examples 1-8, and the other examples are the same. Example

[0183] A water-based fire-retardant coating comprises the following raw materials in parts by weight:

[0184] 36 parts of fluorosilicone epoxy hybrid emulsion;

[0185] 12 portions of hydrophobic silica aerogel;

[0186] Composite microencapsulated flame retardant: 15 parts;

[0187] 8 parts of composite bio-based charring agent;

[0188] 5 parts of complex free radical scavenger;

[0189] Two parts of silane-modified cellulose nanofibers;

[0190] Three parts of short-cut basalt fibers;

[0191] Two parts PCL fiber;

[0192] Three doses of self-healing microcapsules;

[0193] 1.5 parts of microencapsulated third-generation Grubb catalyst;

[0194] 1 part of nano CeO2;

[0195] 2 parts of polyether-modified polydimethylsiloxane

[0196] 2 parts dispersant;

[0197] 3 parts of UV-1577 ultraviolet absorber;

[0198] 21 parts water.

[0199] A preparation process for a water-based fire-retardant coating includes the following steps:

[0200] S1. Weigh the raw materials according to the weight parts, add the fluorosilicone epoxy hybrid emulsion into the dispersion vessel, and stir at a low speed of 300r / min.

[0201] S2. Premix the polyether-modified polydimethylsiloxane, dispersant, UV-1577 ultraviolet absorber with 40% of the total water volume, stir until uniform, and then slowly add it to the dispersion vessel of step S1 to mix evenly with the base emulsion.

[0202] S3. Under stirring at 500 r / min, add hydrophobic silica aerogel, composite microencapsulated flame retardant, composite bio-based charring agent, composite free radical scavenger and nano CeO2 to the dispersion vessel in sequence, increase the stirring speed to 1200 r / min and stir for 30 min.

[0203] S4. Reduce the stirring speed to 300 r / min, add silane-modified cellulose nanocrystals, short-cut basalt fibers and PCL fibers in sequence, and stir for 10 min.

[0204] S5. Maintain low-speed stirring, add self-healing microcapsules and microencapsulated third-generation Grubb catalyst in sequence, stir for 20 minutes to ensure that they are evenly distributed in the whole system.

[0205] S6. Use the remaining water to adjust the viscosity of the coating to 2000 mPa·s, stir at 150 r / min for 8 min, and discharge to obtain the water-based fireproof coating.

[0206] In this embodiment, some of the raw materials used are the same as those obtained in Preparation Examples 1-8, and the other examples are the same.

[0207] Comparative Example 1

[0208] The difference between this comparative example and Example 1 is that the fluorosilicone epoxy hybrid emulsion prepared in Example 1 was not added; instead, an equal amount of commercially available epoxy resin emulsion was added.

[0209] Comparative Example 2

[0210] The difference between this comparative example and Example 1 is that the hydrophobic silica aerogel prepared in Example 2 was not added; instead, an equal amount of commercially available nano silica aerogel was added.

[0211] Comparative Example 3

[0212] Ammonium polyphosphate, pentaerythritol, and melamine were mixed evenly in a mass ratio of 20:8:5 and ground through a 200-mesh sieve to obtain a flame retardant mixture.

[0213] The difference between this comparative example and Example 1 is that the composite microencapsulated flame retardant prepared in Preparation Example 3 was not added; instead, an equal amount of flame retardant mixture was added.

[0214] Comparative Example 4

[0215] The difference between this comparative example and Example 1 is that the composite bio-based charring agent prepared in Example 4 was not added; instead, alkali lignin was added.

[0216] Comparative Example 5

[0217] The difference between this comparative example and Example 1 is that the composite free radical scavenger prepared in Preparation Example 5 was not added; instead, an equal amount of antimony trioxide was added.

[0218] Comparative Example 6

[0219] The difference between this comparative example and Example 1 is that the self-healing microcapsules prepared in Preparation Example 6 were not added.

[0220] test:

[0221] I. Fire resistance performance test

[0222] The water-based waterproof coatings obtained in each embodiment and comparative example were uniformly applied to the surface of a substrate (standard concrete slab) conforming to the requirements of GB12441-2018 standard using a scraper application method. The wet film thickness was controlled, and after curing at 25℃ and 50% relative humidity for 21 days, the dry film thickness reached 2.0 mm. Test panels for other performance tests were prepared according to the relevant standards.

[0223] Testing Standard: GB 12441-2018 Decorative Fire-Retardant Coatings

[0224] 1. Fire resistance performance: According to the fire resistance performance specification in section 5.3 of the standard, the large plate burning method is used for testing, and the fire resistance time (min) is recorded.

[0225] 2. Flame propagation performance: According to the provisions of section 5.4 of the standard, the tunnel burning method was used for testing, and the flame propagation ratio was recorded.

[0226] 3. Flame Retardant Performance: The flame retardant performance was tested using the small chamber method according to section 5.5 of the standard. The mass loss (g) and char volume (cm³) were recorded. 3 ).

[0227] II. Water Resistance Test

[0228] Test standard: GB / T 1733-1993 Determination of water resistance of paint film

[0229] Test method: Method A in the standard: Immersion method. The coated test panel was immersed in deionized water for 30 days. After recovery, its fire resistance time was retested according to GB 12441-2018, and the fire resistance time retention rate (%) was calculated.

[0230] III. Adhesion Test

[0231] Test standard: GB / T 9286-2021 Paints and varnishes - Cross-cut test

[0232] Test method: Perform a cross-cut test according to the standard, with a spacing of 1 mm. Evaluate the adhesion level (0-5) according to the grading standard in Table 1 of the standard.

[0233] IV. Flexibility Test

[0234] Test standard: GB / T 1731-2020 Determination of flexibility of paint film and putty film

[0235] Test method: Given the relatively thick fire-retardant coating, a flexibility tester (bar method) was used for testing, referring to this standard. The smallest bar diameter at which the coating did not crack was selected, and the bar diameter (mm) was recorded as the flexibility index.

[0236] V. Artificial Weathering Resistance Test

[0237] Test Standard: GB / T 23987-2009 Artificial Weathering Exposure of Paint and Varnish Coatings to Fluorescent Ultraviolet Light and Water

[0238] Test method: The test was conducted according to the UV / condensation cycle test method specified in the standard. The coating test panels were placed in an aging chamber for accelerated aging for 1000 hours. The fire resistance time was then retested according to GB 12441-2018, and the fire resistance time retention rate (%) was calculated using the formula shown below:

[0239] Fire resistance time retention rate (%) = (fire resistance time of the specimen after aging / fire resistance time of the specimen before aging) × 100%.

[0240] The test results are shown in Table 1.

[0241] VI. Summary of Results

[0242] Table 1

[0243]

[0244] VII. Discussion of Results

[0245] As shown in Table 1, the water-based fire-retardant coatings prepared in Examples 1-3 of this invention produce coatings with excellent fire resistance and environmental durability, achieving a synergistic improvement in functionality and mechanical properties.

[0246] Firstly, the fire resistance times of Examples 1-3 all significantly exceeded those of the comparative examples, with Example 3 achieving the best result at 135 minutes. This indicates that the present invention constructs a highly efficient fire barrier through the synergistic effect of fluorosilicone-epoxy hybrid emulsion, composite microencapsulated flame retardant, composite bio-based charring agent, and composite free radical scavenger. Simultaneously, the extremely low flame spread ratio, mass loss, and char volume of the examples demonstrate that they effectively inhibit flame spread and promote the formation of a dense, stable, and high-strength char layer.

[0247] Secondly, after 30 days of immersion in water and 1000 hours of UV aging, the fire resistance retention rate of the examples was higher than 90%, significantly better than that of the comparative examples. This is mainly due to the inherent density, hydrophobicity, and UV resistance of the fluorosilicone epoxy hybrid emulsion film, as well as the long-lasting thermal insulation protection provided by the stable nanoporous structure of the hydrophobic silica aerogel, ensuring that the coating can maintain its long-term effective fire resistance function even in harsh environments.

[0248] Third, all embodiments exhibited excellent adhesion and flexibility, demonstrating the synergistic toughening effect of the reinforcing fibers and nanofibers. Silane-modified cellulose nanofibers reinforced the resin matrix at the nanoscale, significantly improving the coating's density and substrate adhesion; short-cut basalt fibers constructed a three-dimensional network skeleton at the micrometer scale, effectively enhancing the coating's macroscopic strength and crack resistance; while PCL fibers melted in the initial stage of heating, not only promoting the fusion and uniform expansion of the flame-retardant system components, but also acting as a binder to further strengthen the char layer structure. This multi-scale, multi-mechanism synergistic reinforcement system ensures that the coating maintains excellent mechanical strength and applicability to construction while possessing outstanding fire resistance.

[0249] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0250] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the scope defined by the invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A water-based fire-retardant coating, characterized in that: Including the following parts by weight of raw materials: 30-36 parts of fluorosilicone epoxy hybrid emulsion; 9-12 parts of hydrophobic silica aerogel; 12-15 parts of composite microencapsulated flame retardant; 5-8 parts of composite bio-based charring agent; 3-5 parts of complex free radical scavenger; 1-2 parts of silane-modified cellulose nanofibers; 2-3 parts of short-cut basalt fiber; 1-2 parts of PCL fiber; 2-3 portions of self-repairing microcapsules; 0.5-1.5 parts of Grubb catalyst; Nano CeO2 0.5-1 part; 1-2 parts leveling agent; Dispersant 0.5-2 parts; 1-3 parts of UV absorber; 18-25 parts water; The preparation method of the composite microencapsulated flame retardant is as follows: C1. Polycaprolactone was dissolved in dichloromethane to obtain a PCL solution; ammonium polyphosphate, pentaerythritol and melamine were mixed evenly and ground through a 200-mesh sieve to obtain a flame retardant mixture; the flame retardant mixture was dispersed in deionized water, sodium dodecyl sulfate was added, and the mixture was sheared at 8000-12000 r / min for 10-15 min to obtain a dispersion; the dispersion was added dropwise to the PCL solution, sheared at 15-20 min, stirred in a 40℃ water bath for 2 h, centrifuged, washed 3 times with deionized water, and dried at 60℃ for 12 h to obtain PCL flame retardant microspheres; The mass ratio of polycaprolactone to dichloromethane is 1:(4-10); The mass ratio of ammonium polyphosphate, pentaerythritol, melamine, deionized water, and sodium dodecyl sulfate is 40:16:10:200:

1. The mass ratio of the PCL solution to the dispersion is (4-6):1; C2. Disperse the PCL flame-retardant microspheres obtained in step C1 in deionized water and sonicate for 30-40 min to obtain a suspension; dissolve magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water to obtain a mixed salt solution; add the mixed salt solution dropwise to the suspension, adjust the pH to 9.3-9.7, stir in a 60℃ water bath for 6 h, centrifuge, wash until neutral, and dry to obtain crude capsules; The mass ratio of the PCL flame-retardant microspheres to deionized water is 1:(12-18); The mass ratio of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and deionized water is 7:3.6:100; The mass ratio of the suspension to the mixed salt solution is 3:1; C3. Disperse the crude capsules obtained in step C2 in an aqueous sodium borate solution, stir at 80°C for 2 hours, centrifuge, wash three times with deionized water, and dry at 60°C for 12 hours to obtain a composite microencapsulated flame retardant. The mass ratio of the crude product capsules to the sodium borate aqueous solution is 1:(8-12); The sodium borate aqueous solution has a mass fraction of 0.5-1.5%; The preparation method of the self-healing microcapsules is as follows: F1. Mix dicyclopentadiene, ethyl cellulose and Span-80, and stir to dissolve at 40°C to obtain the oil phase; The mass ratio of dicyclopentadiene, ethyl cellulose and Span-80 is 125:10:4; F2. Dissolve gelatin and gum arabic in deionized water and stir at 50°C to dissolve. Adjust the pH to 4.5 with acetic acid solution to obtain an aqueous phase. Add the oil phase obtained in step F1 to the aqueous phase and emulsify at high speed of 800-1200 r / min for 10 min to form an oil-in-water emulsion. The mass ratio of gelatin, gum arabic, and deionized water is 1:1:(45-55); the mass ratio of oil phase to water phase is 1:(5-7); F3. Cool the oil-in-water emulsion obtained in step F2 to 45°C, adjust the pH to 9.0 with NaOH solution, add glutaraldehyde solution, and stir for 2 hours; then add hydrochloric acid solution to adjust the pH to 3.0, and continue the reaction for 1 hour; dilute the reaction solution with deionized water, centrifuge, wash 3 times with deionized water, and vacuum dry at 40°C for 12 hours to obtain self-healing microcapsules. The glutaraldehyde solution has a mass fraction of 50%, and the mass ratio of glutaraldehyde to the oil-in-water emulsion is 3:

50. The Grubb catalyst is a third-generation Grubb catalyst that has undergone microencapsulation; the leveling agent is polyether-modified polydimethylsiloxane; the dispersant is a mixture of sodium polyacrylate and polymaleic anhydride in a mass ratio of 2:1; and the ultraviolet absorber is one or more of 2-hydroxy-4-methoxybenzophenone and triazine ultraviolet absorbers.

2. The water-based fire-retardant coating according to claim 1, characterized in that: The preparation method of the fluorosilicone epoxy hybrid emulsion is as follows: A1. Mix epoxy resin E-44, γ-glycidoxypropyltrimethoxysilane, methyl methacrylate, butyl acrylate, dodecafluoroheptyl methacrylate and acrylic acid and stir evenly. Add xylene, heat to 110-115℃, and add a xylene solution containing benzoyl peroxide dropwise over 1-2 hours. After the addition is complete, keep the mixture at 110-120℃ for 1-3 hours to obtain the prepolymer. The mass ratio of epoxy resin E-44, γ-glycidoxypropyltrimethoxysilane, methyl methacrylate, butyl acrylate, dodecafluoroheptyl methacrylate, acrylic acid, benzoyl peroxide and xylene is 40:8:5:15:3:2:0.8:

10. A2. Cool the prepolymer obtained in step A1 to 60°C, add triethylamine, stir for 30 min, add deionized water, and pre-emulsify at 800 r / min for 15 min to obtain a pre-emulsion. The molar ratio of triethylamine to epoxy groups is 0.8:1; The mass ratio of deionized water to prepolymer is 1:(1.5-3); A3. Heat the pre-emulsion obtained in step A2 to 75°C, add ammonium persulfate aqueous solution, and react under nitrogen protection for 1-2 hours; then heat to 85°C and keep warm for 1 hour; cool the reaction solution to 65°C and let it stand under a vacuum of -0.095MPa for 12-14 hours to obtain fluorosilicone epoxy hybrid emulsion. The mass ratio of ammonium persulfate to pre-emulsion is 1:

50.

3. The water-based fire-retardant coating according to claim 1, characterized in that: The preparation method of the hydrophobic silica aerogel is as follows: B1. At 30℃, tetraethyl orthosilicate, anhydrous ethanol and deionized water are mixed evenly, and the pH is adjusted to 2-3 with 0.5mol / L hydrochloric acid. The mixture is then hydrolyzed for 1 hour with stirring at 300r / min to obtain a transparent sol. The mass ratio of tetraethyl orthosilicate, anhydrous ethanol, and deionized water is 3:7:

1. B2. Add ammonia to adjust the pH of the transparent sol obtained in step B1 to 7-8, add hexadecyltrimethylammonium bromide, and let it stand at 40°C for 4 hours to gel, to obtain a wet gel. Soak the wet gel in anhydrous ethanol at 50°C for 24 hours to age, changing the ethanol 3 times during the process. The mass ratio of hexadecyltrimethylammonium bromide to tetraethyl orthosilicate is 1:(18-22); B3. The aged gel obtained in step B2 is immersed in a hexane solution containing heptadecanodecyltrimethoxysilane with a mass fraction of 5-20%, reacted at 60°C for 6 hours, dried at 80°C for 4 hours, vacuum dried at 150°C for 2 hours, and ground through a 200-mesh sieve to obtain hydrophobic silica aerogel. The mass ratio of the gel to the hexane solution of heptadecafluorodecyltrimethoxysilane is 1:(8-12).

4. The water-based fire-retardant coating according to claim 1, characterized in that: The preparation method of the composite bio-based charring agent is as follows: D1. Alkali lignin, 2,3-epoxypropyltrimethylammonium chloride and deionized water were mixed and stirred at 60°C for 6 hours. The pH was adjusted to 10-11, centrifuged, washed with deionized water until neutral, and dried at 60°C for 12 hours to obtain quaternized lignin. The mass ratio of the alkali lignin, 2,3-epoxypropyltrimethylammonium chloride, and deionized water is 6:1.6:

30. D2. Place rice husk powder in a muffle furnace and heat it to 600℃ at 3℃ / min under nitrogen protection, and keep it at that temperature for 2h. After natural cooling, soak it in a 2mol / L HNO3 solution for 12h, wash it with deionized water until neutral, and vacuum dry it at 60℃ for 12h to obtain porous biochar. The mass ratio of rice husk powder to HNO3 solution is 1:5; D3. Mix the quaternized lignin obtained in step D1, the porous biochar obtained in step D2, and sodium alginate, add deionized water, stir at 80°C for 1 hour, and spray dry to obtain a composite bio-based char agent. The inlet temperature of the spray drying operation is 180-200℃, and the outlet temperature is 85-95℃; The mass ratio of the quaternized lignin, porous biochar, sodium alginate, and deionized water is 3:5:2:

100.

5. The water-based fire-retardant coating according to claim 1, characterized in that: The preparation method of the composite free radical scavenger is as follows: E1. Mix citric acid, urea and L-cysteine ​​evenly, heat to 190-200℃ at a rate of 5℃ / min under a nitrogen atmosphere, and keep warm for 2-3h to obtain carbon quantum dot precursor. Dissolve the obtained carbon quantum dot precursor in deionized water and ultrasonically disperse for 30min to obtain carbon quantum dot precursor solution. The mass ratio of citric acid, urea and L-cysteine ​​is 5:4:1; The mass ratio of the carbon quantum dot precursor to deionized water is 1:(8-12); E2. Add ammonium tetrathiomolybdate, boric acid and ascorbic acid to the carbon quantum dot precursor solution, heat to 170-180℃ under nitrogen atmosphere, react for 12-14h, cool naturally to room temperature, centrifuge, wash 3 times with deionized water, dry at 60℃ for 12-24h, grind through a 200-mesh sieve to obtain the composite free radical scavenger. The mass ratio of the ammonium tetrathiomolybdate, boric acid, ascorbic acid, and carbon quantum dot precursor solution is 1:0.4:0.1:

10.

6. The water-based fire-retardant coating according to claim 1, characterized in that: The silane-modified cellulose nanofibers are cellulose nanofibers obtained through pretreatment. The length of the cellulose nanofibers is 200-500 nm, the diameter is 10-30 nm, and the aspect ratio is (10-30):

1. The length of the short-cut basalt fibers is 1-3 mm, the fiber diameter is 10-18 μm, the tensile strength of the single filament is not less than 3000 MPa, and the heat resistance temperature is not less than 600℃. The length of the PCL fibers is 2-4 mm, and the fiber diameter is 15-25 μm.

7. A method for preparing a water-based fire-retardant coating according to any one of claims 1-6, characterized in that: The specific steps are as follows: S1. Weigh the raw materials according to the weight parts, add the fluorosilicone epoxy hybrid emulsion into the dispersion vessel, and stir at a low speed of 300-400r / min. S2. Premix the leveling agent, dispersant, UV absorber and 30-50% of the total water volume with water, stir until uniform, and then slowly add to the dispersion vessel in step S1, and mix evenly with the base emulsion. S3. While stirring at 400-600 r / min, add hydrophobic silica aerogel, composite microencapsulated flame retardant, composite bio-based charring agent, composite free radical scavenger and nano CeO2 to the dispersion vessel in sequence, increase the stirring speed to 1200-1500 r / min and stir for 20-30 min. S4. Reduce the stirring speed to 300-400 r / min, add silane-modified cellulose nanofibers, short-cut basalt fibers and PCL fibers in sequence, and stir for 10-15 min to ensure that the fibers are evenly dispersed without obvious entanglement; S5. Maintain low-speed stirring, add self-healing microcapsules and Grubb catalyst in sequence, stir for 15-20 minutes to ensure uniform distribution in the whole system; S6. Use the remaining water to adjust the viscosity of the coating to 1500-2500 mPa·s, stir at 100-200 r / min for 5-10 min, and discharge to obtain the water-based fireproof coating.

Images