A wood coating that combines durability, hydrophobicity, and flame retardancy, and its preparation method.

Abstract

This invention discloses a durable, hydrophobic, and flame-retardant wood coating and its preparation method, belonging to the field of timber structure building protection. The wood coating of this invention is a two-layer system, comprising a flame-retardant primer and a hydrophobic topcoat. The flame-retardant primer uses tung oil modified from natural rubber via the Diels-Alder reaction as the film-forming matrix and biochar prepared from agricultural waste straw as a bio-based flame-retardant filler. The hydrophobic topcoat uses polydimethylsiloxane / nano-silica as the core functional component. This invention uses fully bio-based raw materials as its core, and the preparation process is simple and green. Through molecular structure modification and synergistic design of the two-layer system, the coating simultaneously possesses excellent hydrophobicity, flame retardancy and smoke suppression, UV stability, and long-term outdoor durability. After being applied to the wood surface, it can simultaneously solve the core pain points of wood's flammability, moisture absorption, and poor weather resistance, showing broad application prospects in the fields of modern timber structure buildings and the protection of traditional timber architectural heritage.

Description

Technical Field

[0001] This invention belongs to the field of timber structure protection, specifically relating to a wood coating that is durable, hydrophobic, and flame-retardant, and its preparation method. Background Technology

[0002] Driven by global carbon neutrality strategies and sustainable development goals, natural wood, as a renewable and carbon-neutral green building material, has been widely used in modern timber-framed buildings and the preservation of traditional timber-framed architectural heritage. However, natural wood has three inherent defects that severely limit its long-term service life in complex outdoor environments: First, the lignocellulose in wood contains a large number of hydrophilic hydroxyl groups, making it highly hygroscopic and prone to dimensional deformation, mold, and decay under fluctuating temperature and humidity; second, wood is a typical flammable biomass material, which undergoes violent pyrolysis and combustion when exposed to fire, releasing large amounts of heat and toxic fumes, and the flame spreads rapidly, posing a serious threat to building fire safety; third, the unsaturated groups and lignocellulose structure in wood are prone to photo-oxidative degradation under long-term ultraviolet radiation, leading to deterioration of mechanical and protective properties. Therefore, developing environmentally friendly, high-performance protective coatings that simultaneously improve the hydrophobicity, flame retardancy, and long-term weather resistance of wood has become an urgent technical need in the fields of wood protection and timber-framed engineering.

[0003] Currently, most mainstream wood protective coatings are petroleum-based polymer materials. While they offer excellent protective performance, they suffer from drawbacks such as non-renewable raw materials, high emissions of volatile organic compounds (VOCs), and significant environmental pollution, contradicting the global low-carbon development philosophy. Against this backdrop, bio-based coatings using renewable biomass resources have become a research hotspot in the field of wood protection. Tung oil, a traditional plant-based protective material in my country, has a history of thousands of years of application in wood protection due to its excellent film-forming properties, water resistance, and wide availability. However, pure tung oil has significant application drawbacks: the numerous conjugated carbon-carbon double bonds in its triglyceride structure are prone to oxidative degradation under ultraviolet irradiation, resulting in poor long-term weather resistance; furthermore, pure tung oil is flammable and has poor char-forming ability, failing to improve the fire safety of wood and even increasing the fire risk of the substrate.

[0004] In existing research on tung oil modification, the Diels-Alder cycloaddition reaction has been proven to be an effective method for improving tung oil properties. It can consume the conjugated double bonds in tung oil, reduce oxidative active sites, and improve the film-forming properties and thermal stability of tung oil. Meanwhile, biochar derived from agricultural and forestry waste, as a green and low-cost bio-based flame retardant, is also widely used in bio-based flame retardant systems. However, current research still faces significant technical bottlenecks: most modified tung oil coatings focus only on improving a single property, making it difficult to achieve a synergistic improvement in hydrophobicity, flame retardancy, and weather resistance; the introduction of flame-retardant fillers often damages the hydrophobicity and film-forming properties of the coating, leading to incompatibility between flame retardancy and water resistance; in addition, most existing studies remain at the stage of small-scale performance testing in the laboratory, lacking verification of protective effects under real full-scale fire scenarios in wooden structures, resulting in a significant scale gap between laboratory research and actual engineering applications. Summary of the Invention

[0005] To address the aforementioned issues, this invention discloses a wood coating that combines durability, hydrophobicity, and flame retardancy, along with its preparation method. Using fully bio-based raw materials as the core, the preparation process is simple and environmentally friendly. Through molecular structure modification and synergistic design of a bilayer system, the coating simultaneously possesses excellent hydrophobicity, flame retardancy and smoke suppression, UV stability, and long-term outdoor durability.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A durable, hydrophobic, and flame-retardant wood coating comprises a two-layer system consisting of a flame-retardant primer and a hydrophobic topcoat. The flame-retardant primer, by weight, includes the following components: 80-120 parts of natural rubber-modified tung oil, 8-12 parts of straw biochar, and 200-300 parts of organic solvent. The hydrophobic topcoat, by weight, includes the following components: 1.2-1.8 parts of hydrophobic fumed silica, 0.5-0.8 parts of polydimethylsiloxane prepolymer, 0.05-0.09 parts of curing agent, and 45-55 parts of anhydrous ethanol.

[0007] Furthermore, the optimal formulation of the flame-retardant primer is: 100 parts of natural rubber modified tung oil, 10 parts of straw biochar, and 250 parts of organic solvent; the optimal formulation of the hydrophobic topcoat is: 1.5 parts of hydrophobic fumed silica, 0.68 parts of polydimethylsiloxane prepolymer, 0.07 parts of curing agent, and 50 parts of anhydrous ethanol.

[0008] Furthermore, the natural rubber modified tung oil is prepared by a Diels-Alder cycloaddition reaction, and the raw materials include 40-50 parts of tung oil, 3-5 parts of natural rubber, and 90-110 parts of anhydrous xylene by weight. This reaction consumes the oxidizable conjugated double bonds in the tung oil, thereby inhibiting the photo-oxidative degradation of tung oil from the source, while forming a cross-linked network structure to improve the film-forming properties and thermal stability of the coating.

[0009] Furthermore, the straw biochar is prepared from agricultural waste straw through oxygen-limited slow pyrolysis and ball milling, with a particle size of 300-350 mesh, a pyrolysis temperature of 500-600℃, and a pyrolysis time of 1-3h. Its inherent aromatic carbon skeleton and porous structure can act as a thermal barrier to inhibit heat transfer, while its natural silicon-containing components can catalyze the formation of a dense heat-resistant carbon layer during combustion, achieving efficient flame retardancy and smoke suppression.

[0010] Furthermore, the hydrophobic fumed silica nanoparticles have a particle size of 30-50 nm; the organic solvent is anhydrous xylene; the polydimethylsiloxane prepolymer is hydroxyl-terminated polydimethylsiloxane; and the curing agent is an organotin curing agent.

[0011] This invention also provides a method for preparing the above-mentioned durable, hydrophobic, and flame-retardant wood coating, comprising the following steps: S1 Preparation of natural rubber modified tung oil: Natural rubber and anhydrous xylene are mixed and added to a three-necked flask equipped with a reflux condenser and nitrogen inlet and outlet. High-purity nitrogen is introduced for 10-20 minutes to purge residual air from the system. Under a stable nitrogen atmosphere, the mixture is continuously stirred at 250-350 rpm, heated to 70-90℃ and held for 4 hours to completely dissolve the natural rubber, resulting in a uniform and transparent rubber solution. Refined tung oil is added to the rubber solution and stirred for 10 minutes until homogeneous. Under continuous stirring and nitrogen protection, the temperature is raised to 120-140℃ and held for 6-10 hours to complete the Diels-Alder cycloaddition reaction, yielding natural rubber modified tung oil.

[0012] S2 Preparation of straw biochar: Collected agricultural waste straw is repeatedly rinsed with deionized water to remove surface dust, soil and soluble impurities, and dried at 80℃ for 24 hours to constant weight; the completely dried straw is crushed using a high-speed universal pulverizer and placed in a tube furnace, heated to 500~600℃ at a constant heating rate of 3~8℃ / min under nitrogen atmosphere, and pyrolyzed with limited oxygen for 1~3 hours; after natural cooling to room temperature under nitrogen protection, crude biochar is obtained, and the crude biochar is placed in a ball mill and ball-milled for 0.5~1.5 hours, vacuum dried at 60℃ for 10~14 hours to constant weight, and sealed for storage to obtain straw biochar.

[0013] S3 Preparation of flame retardant primer: Add straw biochar to natural rubber modified tung oil according to the formula, heat to 50~70℃, and stir continuously at 250~350rpm for 25~35min to fully wet and initially disperse the biochar particles in the polymer matrix; then ultrasonically disperse in an ice water bath for 25~35min to eliminate particle agglomeration and obtain a stable and uniform flame retardant primer dispersion; S4 Preparation of hydrophobic topcoat: Disperse hydrophobic fumed silica nanoparticles in anhydrous ethanol according to the ratio, add polydimethylsiloxane prepolymer and curing agent, seal and stir at room temperature for 25-35 min, then ultrasonically disperse in an ice water bath for 20-30 min to obtain a uniform dispersion; centrifuge the dispersion at 2500-3500 rpm for 2-5 min to remove trace amounts of undispersed agglomerates, and take the upper homogeneous liquid to obtain the hydrophobic topcoat dispersion.

[0014] Further, the optimal process parameters for step S1 are: dissolution temperature 80℃, dissolution time 4h, stirring speed 300rpm; cycloaddition reaction temperature 130℃, reaction time 8h. The optimal process parameters for step S2 are: pyrolysis temperature 550℃, pyrolysis time 2h, heating rate 5℃ / min; ball milling time 1h, vacuum drying temperature 60℃, drying time 12h. The optimal process parameters for step S3 are: stirring temperature 60℃, stirring time 30min, stirring speed 300rpm; ice-water bath ultrasonication time 30min. The optimal process parameters for step S4 are: room temperature stirring time 30min, ice-water bath ultrasonication time 25min, centrifugation speed 3000rpm, centrifugation time 3min.

[0015] The present invention also provides a construction method for the above-mentioned wood coating, comprising the following steps: (1) uniformly brushing the flame-retardant primer onto the wood surface, placing it in a ventilated fume hood at room temperature for 20-28 hours, and then curing it in a convection oven at 70-90°C for 1-3 hours to obtain a wood sample coated with primer; (2) spraying the hydrophobic topcoat onto the surface of the wood sample coated with primer at a working pressure of 25-35 psi, and curing it at room temperature for 10-14 hours to complete the coating construction.

[0016] Furthermore, the optimal construction process is as follows: after applying the primer, let it stand at room temperature for 24 hours, then cure it in an oven at 80°C for 2 hours; spray the topcoat at a working pressure of 30 psi and cure it at room temperature for 12 hours.

[0017] The beneficial effects of this invention are as follows: (1) Fully bio-based green design with a wide range of raw material sources and environmental protection: This invention uses natural tung oil, natural rubber and agricultural waste straw as core raw materials to replace traditional petroleum-based polymers and flame retardants. The raw materials are renewable, low cost, and simple preparation process. There are no toxic or harmful raw materials added, which is in line with the concept of green and low-carbon development and is suitable for large-scale production and engineering applications.

[0018] (2) Molecular-level modification to improve the weather resistance of coatings from the source: This invention consumes the oxidizable conjugated carbon-carbon double bonds in tung oil through the Diels-Alder cycloaddition reaction, reduces the oxidative active sites in the polymer matrix, and forms a dense cross-linked network structure, thereby inhibiting the photo-oxidative degradation of tung oil from the source and solving the core problem of poor long-term weather resistance of pure tung oil coatings.

[0019] (3) Dual-layer system synergistic design to achieve multi-functional integrated protection: The present invention constructs a dual-layer protection system of "flame retardant primer + hydrophobic topcoat". The primer provides basic protection for wood in terms of flame retardancy and weather resistance through the synergistic effect of modified tung oil and straw biochar. The topcoat endows wood with excellent hydrophobicity through the micro-nano hierarchical rough structure constructed by low surface energy PDMS and nano silica. At the same time, it further enhances the UV shielding ability of the coating, realizing the synergistic improvement of wood hydrophobicity, flame retardancy and smoke suppression and weather resistance, and solving the technical bottleneck of the incompatibility between flame retardancy and hydrophobicity of traditional coatings.

[0020] (4) Excellent comprehensive protective performance and outstanding engineering application value: After the coating of the present invention is applied to the surface of wood, the static water contact angle of the wood can reach 127.8° and the limiting oxygen index can be increased to 33.0%, reaching the standard of flame-retardant materials. Compared with pure wood, the peak heat release rate of the coated wood is reduced by 45.6%, the total heat release is reduced by 42.0%, and the total smoke release is reduced by 72.6%, achieving efficient flame retardancy, smoke suppression and toxicity reduction. After 90 days of natural outdoor aging, the hydrophobic retention rate of the coating is still above 95%, and the flame retardant performance decay is less than 20%, which has excellent long-term outdoor service stability. Full-scale fire numerical simulation results confirm that the coating can effectively inhibit the spread of fire in wooden structures, delay the occurrence of flashover, and delay the occurrence time of the fire hazard peak by 150~200s, providing a key safety time window for personnel evacuation and fire rescue. It has broad application prospects in the fields of modern wooden structures and the protection of traditional wooden architectural heritage. Attached Figure Description

[0021] Figure 1 This is a diagram showing the steps involved in the coating synthesis.

[0022] Figure 2 The images include SEM images, FTIR analysis, and EDS analysis plots.

[0023] Figure 3 The image shows the results of the hydrophobic angle test.

[0024] Figure 4 The image shows the results of the thermogravimetric analysis (TGA).

[0025] Figure 5 Figure showing the test results of a cone calorimeter.

[0026] Figure 6 Limiting oxygen index test results graph.

[0027] Figure 7 Durability test results diagram.

[0028] Figure 8 Schematic diagram of flame retardant mechanism. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Example 1

[0030] This embodiment provides a wood coating that is durable, hydrophobic, and flame-retardant, consisting of a flame-retardant primer and a hydrophobic topcoat (denoted as TOR-BC): Flame-retardant primer formula: 100g natural rubber modified tung oil, 10g straw biochar, 250g anhydrous xylene; Hydrophobic topcoat formulation: 1.5g hydrophobic fumed silica nanoparticles (40nm), 0.68g polydimethylsiloxane prepolymer, 0.07g organotin curing agent, and 50g anhydrous ethanol.

[0031] The preparation method includes the following steps: S1 Preparation of natural rubber modified tung oil: Add 4g of natural rubber and 100g of anhydrous xylene to a 500mL three-necked flask, purge with high-purity nitrogen for 15min to purge air; heat to 80℃ under stirring at 300rpm, keep warm for 4h to completely dissolve the natural rubber, and obtain a transparent rubber solution; add 46g of refined tung oil and stir for 10min to mix evenly, heat to 130℃ under nitrogen protection, keep warm for 8h to complete the Diels-Alder reaction, and obtain natural rubber modified tung oil; S2 Preparation of straw biochar: Wash straw, dry at 80℃ for 24h to constant weight, pulverize and place in a tube furnace, heat to 550℃ at 5℃ / min under nitrogen atmosphere, and perform oxygen-limited pyrolysis for 2h; after natural cooling, ball mill for 1h, vacuum dry at 60℃ for 12h to constant weight, and obtain 325 mesh straw biochar; S3 Preparation of flame-retardant primer: Add 10g of straw biochar to 100g of natural rubber modified tung oil, stir at 300rpm for 30min at 60℃, and ultrasonically disperse in an ice-water bath for 30min to obtain a flame-retardant primer dispersion; Preparation of hydrophobic topcoat: Disperse 1.5g of hydrophobic nano-silica in 50g of anhydrous ethanol, add 0.68g of PDMS prepolymer and 0.07g of curing agent, seal and stir at room temperature for 30min, ultrasonically disperse in an ice-water bath for 25min, centrifuge at 3000rpm for 3min, and take the upper homogeneous liquid to obtain the hydrophobic topcoat.

[0032] Application method: Apply flame-retardant primer to the surface of poplar wood sample by brushing, place at room temperature and ventilate for 24 hours, and then cure in an 80℃ oven for 2 hours; then spray hydrophobic topcoat onto the primer surface at a pressure of 30psi, and cure at room temperature for 12 hours to complete the coating.

[0033] Comparative Example 1 This comparative example is a wood sample coated with pure tung oil (denoted as TO). Pure tung oil was brushed onto the surface of poplar wood, placed at room temperature and ventilated for 24 hours, and cured in an oven at 80°C for 2 hours. There was no hydrophobic top coating, and the other conditions were the same as in Example 1.

[0034] Comparative Example 2 This comparative example is a wood sample coated with natural rubber modified tung oil (denoted as TOR). Only the natural rubber modified tung oil in Example 1 was used as the primer. No straw biochar was added, and no hydrophobic topcoat was applied. The other coating conditions were the same as in Example 1.

[0035] Comparative Example 3 This comparative example is an untreated wood sample (pure wood).

[0036] Performance testing and characterization Figure 2 The SEM-EDS and Fourier transform infrared (FTIR) results of the samples show that the surface of pure wood exhibits obvious longitudinal tracheids and a porous structure; TO coating only partially fills the porous structure, TOR coating forms a continuous film, while the TOR-BC coating of this invention completely masks the wood structure, resulting in a uniform and dense surface. FTIR results show that the -OH peak is strong in pure wood, and the -OH peak gradually weakens after TO and TOR coatings. The C=C double bond peak of TOR is significantly lower than that of TO, confirming the occurrence of the DA reaction. TOR-BC exhibits a Si-O-Si characteristic peak in the 1000~1100 cm⁻¹ range, verifying the successful construction of the hydrophobic topcoat. EDS elemental mapping shows that the C, O, P, and Si elements in the TOR-BC coating are uniformly distributed throughout the entire coating range without agglomeration, proving that the coating is continuous and the components are uniformly dispersed.

[0037] Figure 3 The results of contact angle tests for each group of samples show that the static water contact angle of pure wood is only about 42°, which increases to about 85° after TO coating and to about 98° after TOR coating. The contact angle of the TOR-BC coating of this invention is significantly increased to about 130°, which is 208% higher than that of pure wood and 52% higher than that of pure tung oil, achieving a high level of hydrophobicity. Water droplets form a complete sphere on the coating surface without spreading, demonstrating a significant hydrophobic protective effect.

[0038] Figure 4 The thermogravimetric analysis results show that the char residue of wood coated with the TOR-BC coating of this invention increased from 15.2% to 28.6% at 600℃, the maximum rate of thermal weight loss decreased from 1.02% / ℃ to 0.43% / ℃, and the initial thermal degradation temperature increased by 49℃ compared with pure wood. This significantly improved the thermal stability of the wood and laid the core foundation for achieving high-efficiency flame retardant performance.

[0039] Figure 5The results of the cone calorimeter test show that, compared with pure wood, the peak heat release rate of wood coated with the TOR-BC coating of this invention is reduced by 45.6%, the total heat release is reduced by 42.0%, and the total smoke release is reduced by 72.6%. The flame retardant and smoke suppressant effects are significantly better than those of wood coated with pure tung oil or wood coated with a single modified tung oil. It can effectively suppress the release of heat and toxic smoke during the wood combustion process and greatly reduce the fire risk of wooden structures.

[0040] Figure 6 The limiting oxygen index (LOI) test results show that the LOI of pure wood is only about 19.5%, which is a flammable material. After being coated with TO and TOR, the LOI increases to about 22.5% and 22.8% respectively, with limited flame retardant effect. After the TOR-BC coating of this invention is applied, the LOI of wood is greatly increased to 33.0%, reaching the standard of flame-retardant material, which is 69.2% higher than that of pure wood, and has excellent flame retardant performance.

[0041] Figure 7 These are the durability test results after 90 days of natural outdoor aging. After 90 days of natural outdoor aging, the water contact angle of wood coated with pure tung oil (TO) decreased from the initial 85° to 40°, and the hydrophobic properties were almost completely lost; the water contact angle of wood coated with natural rubber modified tung oil (TOR) decreased to 82°, and the performance degradation was significant; while the water contact angle of wood coated with the TOR-BC coating of this invention remained at 120°, with a hydrophobic retention rate of over 95%. After aging, the peak heat release rate of TO and TOR coated wood rebounded to 330 kW / m² and 300 kW / m², respectively, close to the burning level of pure wood, while the peak heat release rate of TOR-BC coated wood of this invention was only 210 kW / m², and the flame retardant performance degradation rate was less than 20%, confirming that the coating of this invention has excellent long-term outdoor weather resistance and can provide long-term stable hydrophobic and flame retardant protection for wood in complex outdoor environments.

[0042] Figure 8 This is a schematic diagram illustrating the possible flame-retardant mechanism of the present invention. Addressing the fire protection needs of traditional and modern wooden buildings, the TOR-BC coating of this invention can rapidly form a dense and stable char layer containing SiO2 under high fire temperatures. Simultaneously, the added biochar itself is a limited heat-insulating and flame-retardant material. This char layer effectively isolates external heat and oxygen from the wood, inhibiting the release of combustible gases such as CO, CH4, and VOCs produced by wood pyrolysis, thus fundamentally blocking the combustion chain reaction and achieving highly efficient flame retardancy and smoke suppression. Furthermore, the modified tung oil has better durability than ordinary tung oil, enhancing the overall durability of the coating. The multifunctional coating provided by this invention can provide reliable fire safety protection for wooden buildings and wooden architectural heritage.

Claims

1. A wood coating that combines durability, hydrophobicity, and flame retardancy, characterized in that, It consists of a flame-retardant primer and a hydrophobic topcoat; The flame-retardant primer comprises the following components by weight: 80-120 parts of natural rubber modified tung oil, 8-12 parts of straw biochar, and 200-300 parts of organic solvent; The hydrophobic topcoat comprises, by weight, the following components: 1.2-1.8 parts of hydrophobic fumed silica nanoparticles, 0.5-0.8 parts of polydimethylsiloxane prepolymer, 0.05-0.09 parts of curing agent, and 45-55 parts of anhydrous ethanol.

2. The wood coating according to claim 1, characterized in that, The flame-retardant primer comprises the following components by weight: 100 parts of natural rubber modified tung oil, 10 parts of straw biochar, and 250 parts of organic solvent. The hydrophobic topcoat comprises the following components by weight: 1.5 parts hydrophobic fumed silica nanoparticles, 0.68 parts polydimethylsiloxane prepolymer, 0.07 parts curing agent, and 50 parts anhydrous ethanol.

3. The wood coating according to claim 2, characterized in that, The natural rubber modified tung oil is prepared by Diels-Alder cycloaddition reaction, and the raw materials include 40-50 parts of tung oil, 3-5 parts of natural rubber, and 90-110 parts of anhydrous xylene by weight.

4. The wood coating according to claim 2, characterized in that, The straw biochar is prepared from agricultural waste straw through slow pyrolysis under limited oxygen and ball milling, with a particle size of 300-350 mesh, a pyrolysis temperature of 500-600℃, and a pyrolysis time of 1-3 hours.

5. The wood coating according to claim 2, characterized in that, The hydrophobic fumed silica nanoparticles have a particle size of 30-50 nm; the organic solvent is anhydrous xylene; the polydimethylsiloxane prepolymer is hydroxyl-terminated polydimethylsiloxane; and the curing agent is an organotin curing agent.

6. A method for preparing a wood coating that combines durability, hydrophobicity, and flame retardancy as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1 Preparation of natural rubber modified tung oil: Natural rubber is mixed with anhydrous xylene, and the mixture is heated to 70~90℃ under a nitrogen atmosphere and stirred to dissolve, resulting in a uniform and transparent rubber solution; tung oil is added to the rubber solution and stirred evenly, and the mixture is heated to 120~140℃ under a nitrogen atmosphere and kept at this temperature for 6~10h to complete the Diels-Alder cycloaddition reaction, thus obtaining natural rubber modified tung oil; S2 Preparation of straw biochar: After washing, drying and crushing the straw, it is pyrolyzed at 500~600℃ under nitrogen atmosphere with limited oxygen for 1~3h, naturally cooled and then ball-milled for 0.5~1.5h, and then vacuum dried to obtain straw biochar; S3 Preparation of flame retardant primer: Add straw biochar to natural rubber modified tung oil, heat to 50~70℃ and stir to disperse, then disperse by ultrasonication in an ice water bath to obtain a uniform and stable flame retardant primer dispersion. S4 Preparation of hydrophobic topcoat: Hydrophobic fumed silica nanoparticles are dispersed in anhydrous ethanol, polydimethylsiloxane prepolymer and curing agent are added, and after being stirred in a sealed container at room temperature, the mixture is ultrasonically dispersed in an ice-water bath. After centrifugation to remove agglomerates, a hydrophobic topcoat dispersion is obtained.

7. The preparation method according to claim 6, characterized in that, In step S1, the dissolution temperature is 80℃, the dissolution time is 4h, and the stirring speed is 250~350rpm; the cycloaddition reaction temperature is 130℃, and the reaction time is 8h; a nitrogen atmosphere is maintained throughout the reaction, and the nitrogen is introduced for 10~20min to purge the air in the system.

8. The preparation method according to claim 6, characterized in that, In step S2, the pyrolysis temperature is 550℃, the pyrolysis time is 2h, and the heating rate is 3~8℃ / min; the ball milling time is 1h, the vacuum drying temperature is 50~70℃, and the drying time is 10~14h; In step S3, the stirring temperature is 60℃, the stirring time is 25~35min, and the stirring speed is 250~350rpm; the ice-water bath ultrasonic time is 25~35min; In step S4, the room temperature stirring time is 25~35min, the ice-water bath ultrasonic time is 20~30min, the centrifugation speed is 2500~3500rpm, and the centrifugation time is 2~5min.

9. A method for applying the wood coating according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Apply flame-retardant primer evenly to the surface of wood, place it in a room temperature and ventilated environment for 20-28 hours, and then cure it in an oven at 70-90℃ for 1-3 hours to obtain a wood sample coated with primer. (2) Apply the hydrophobic topcoat to the surface of the wood sample coated with primer at a working pressure of 25~35psi and cure at room temperature for 10~14h to complete the coating application.

Images