Modified multilayer perlite composite fireproof board and preparation method thereof

Abstract

The application discloses a modified multilayer perlite composite flame-retardant plate and a preparation method thereof, and belongs to the technical field of composite flame-retardant plate preparation. The preparation method of the modified multilayer perlite composite flame-retardant plate comprises the following steps: step one, processing wood into a flake, then performing vacuum pressure impregnation treatment on the flake by using a composite flame retardant and a preservative, drying, splicing, and obtaining a wood surface layer; step two, respectively preparing inorganic flame-retardant slurry and organic adhesive material; step three, preparing a flame-retardant core layer plate; step four, assembling the wood surface layer and the flame-retardant core layer plate in an alternating paving mode, coating an adhesive between layers, forming a multilayer composite plate blank, pressing, curing, drying, post-treating, and obtaining the modified multilayer perlite composite flame-retardant plate. The composite flame-retardant plate prepared according to the above method has high flame-retardant performance, hydrophobic performance and strength.

Description

Technical Field

[0001] This invention belongs to the field of composite flame retardant board preparation technology, specifically relating to a modified multilayer perlite composite flame retardant board and its preparation method. Background Technology

[0002] In the field of building fire protection and insulation, traditional materials face the challenge of limited or insufficient comprehensive performance. While organic insulation materials possess good thermal insulation properties, they suffer from drawbacks such as flammability, high-temperature dripping, and the release of toxic gases, making them unsuitable for high-fire-resistance environments. Inorganic materials like rock wool, while exhibiting excellent fire resistance, suffer from high thermal conductivity and are prone to crumbling during construction. Perlite, a natural inorganic mineral, forms a porous honeycomb structure after high-temperature expansion, possessing non-combustible, lightweight, and thermal insulation properties. However, its single-layer structure has limitations in impact resistance, moisture resistance, and long-term stability. Modified multi-layer perlite composite fire-retardant boards, by combining expanded perlite with a fire-retardant layer and reinforcing skeleton, and introducing inorganic binders and functional additives, not only retain perlite's core fire-resistant advantages but also enhance the material's mechanical strength, moisture resistance, and high-temperature stability through the synergistic effect of its multi-layer structure. This provides a safer and more durable solution for building exterior walls, firebreaks, and industrial equipment insulation.

[0003] Patent CN108484087A discloses a method for preparing an environmentally friendly biomass composite flame-retardant board material. Using corn stalks and wood as raw materials, and an aqueous solution composed of magnesium chloride, magnesium sulfate, magnesium oxide, and sodium silicate as an inorganic binder, the method employs a hot-pressing process to prepare the environmentally friendly biomass composite flame-retardant board material. The biomass composite flame-retardant board material prepared by this invention exhibits excellent flame-retardant and smoke-suppressing properties, with an ignition time of 410 seconds, meeting the 5-7 minute requirement for high-rise building materials. It can be used as a high-rise building material, ensuring the safe evacuation of personnel during fires and reducing fire hazards. While the biomass composite flame-retardant board material prepared according to the above patent method possesses excellent flame-retardant and smoke-suppressing properties and can meet the fire protection requirements of high-rise buildings, it still has certain drawbacks. The main problem lies in the material's poor water resistance. After long-term use in humid environments, it is prone to changes in its internal structure due to water absorption, leading to decreased strength and deformation. This is mainly because biomass raw materials such as corn stalks are highly absorbent, and the inorganic adhesives used will affect the bonding stability of the raw materials in a humid environment, thereby reducing the overall water resistance of the material. Summary of the Invention

[0004] The purpose of this invention is to provide a modified multilayer perlite composite flame retardant board and its preparation method, which solves the technical problems of low flame retardant performance, waterproof performance and strength of existing composite flame retardant boards.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing a modified multilayer perlite composite flame-retardant board, comprising the following steps: Step 1: Process the wood into thin slices, then use a composite flame retardant and preservative to impregnate the slices under vacuum pressure, dry them, and splice them together to obtain the wood surface layer; Step 2: Mix expanded perlite, magnesium chloride aqueous solution, magnesium oxide, sodium phosphate, lithopone, emulsifier and binder to obtain inorganic flame retardant slurry; mix tetrahydrofuran, composite polymer, composite flame retardant and perlite to obtain organic adhesive material; Step 3: Mix the inorganic flame retardant slurry and the organic adhesive to obtain the flame retardant slurry; then add the flame retardant slurry into the mold and press it to obtain the flame retardant core layer board; Step 4: Assemble the wood surface layer and the flame-retardant core layer in an alternating manner, apply adhesive between the layers to form a multi-layer composite board blank, press, cure, dry, and post-process to obtain the modified multi-layer perlite composite flame-retardant board.

[0006] Preferably, the preparation method of the composite flame retardant includes the following steps: Q1: Add 4-(trifluoromethyl)phenylhydrazine, 3,4-difluoroacetophenone and polyphosphoric acid to a container, heat and stir to mix, cool, adjust pH, extract the aqueous phase with ethyl acetate, dry the extract, rotary evaporate, and purify to obtain organic compound 1; Q2: Organic compound 1 and 4-dimethylaminopyridine were added to dichloromethane and stirred to dissolve. Triethylamine and methacryloyl chloride were added under ice bath conditions. After heating and stirring, dichloromethane was added to dilute the mixture. The solution was then quenched with saturated ammonium chloride solution. The aqueous phase was extracted with dichloromethane, and the organic layer was washed with saturated ammonium chloride. The mixture was dried, filtered, concentrated, purified, and recrystallized to obtain organic compound 2. Q3: Add organic compound 2, dimethyl fluoromalonate, potassium carbonate and acetonitrile to a container, stir and react, then quench with distilled water, extract with dichloromethane, dry, filter, concentrate and purify to obtain a composite flame retardant.

[0007] The synthesis reaction process of the composite flame retardant in the above process is as follows:

[0008] The mass spectrometry analysis results of organic compound 1 were: m / z: 297.06 (100.0%), 298.06 (16.3%), 299.06 (1.3%); the mass spectrometry analysis results of organic compound 2 were: m / z: 365.08 (100.0%), 366.09 (20.7%), 367.09 (2.2%); the mass spectrometry analysis results of the composite flame retardant were: m / z: 515.12 (100.0%), 516.12 (26.4%), 517.12 (4.4%).

[0009] Preferably, in Q1, the ratio of 4-(trifluoromethyl)phenylhydrazine, 3,4-difluoroacetophenone, and polyphosphoric acid is (1.852-2.022) g : (1.024-1.406) g : (9-11) g. The mixture is heated to 110-130℃ and stirred for 3-6 hours. The pH is adjusted to 7-7.2 with a 1 mol / L sodium hydroxide aqueous solution and dried with anhydrous sodium sulfate.

[0010] Preferably, in Q2, the ratio of organic compounds 1,4-dimethylaminopyridine, triethylamine, and methacryloyl chloride is (0.842-0.967) g : (0.464-0.652) g : (0.114-0.205) g : (0.225-0.294) g, the ice bath temperature is 0-1℃, the temperature is raised to 28-30℃ and stirred for 2-3 days, and then dried with anhydrous sodium sulfate.

[0011] Preferably, in Q3, the ratio of organic compound 2, dimethyl fluoromalonate, potassium carbonate and acetonitrile is (0.232-0.357) g : (0.115-0.148) g : (0.326-0.381) g : (2-4) mL, the reaction is stirred for 1-2 h, and then dried with anhydrous sodium sulfate.

[0012] Preferably, the method for preparing the composite polymer includes the following steps: S1: Tetrafluoroterephthalic acid and epichlorohydrin were added to a container, heated and stirred to react, sulfuric acid was added, and the reaction was continued to be heated and stirred. Sodium hydroxide aqueous solution was added and the reaction was continued to be stirred. After the reaction was completed, the product was extracted, allowed to stand, washed, and the oil phase was distilled under reduced pressure to obtain product a. S2: Add 1,8-octanediamine to a container containing ethanol, then add product a, mix well, heat to react, and after the reaction is complete, distill under reduced pressure to obtain product b; S3: Product b, m-diphenylacetonitrile, potassium carbonate and N-bromosuccinimide were added to a container in sequence, stirred and reacted, then distilled water was added, the mixture was distilled under reduced pressure, filtered, washed and dried to obtain the composite polymer.

[0013] The synthesis reaction formula for the composite polymer in the above process is as follows:

[0014] The mass spectrometry analysis results of product a were: m / z: 350.04 (100.0%), 351.04 (15.1%), 352.05 (2.4%); the mass spectrometry analysis results of product b were: m / z: 638.37 (100.0%), 639.37 (33.3%), 640.37 (6.9%), 639.36 (1.5%).

[0015] Preferably, in step S1, the ratio of tetrafluoroterephthalic acid, epichlorohydrin, sulfuric acid, and sodium hydroxide aqueous solution is (1.022-1.147) g : (1.225-1.369) g : (0.06-0.11) g : (1.453-1.658) g, the volume fraction of sulfuric acid is 98 wt%, the concentration of sodium hydroxide aqueous solution is 1 mol / L, the temperature for heating and stirring is 55-65℃, the time is 20-30 min, the temperature is further increased to 70-80℃, the stirring reaction is carried out for 6-8 h, and the stirring reaction is continued for 4-6 h.

[0016] Preferably, in step S2, the ratio of 1,8-octanediamine, ethanol, and product a is (1.122-1.326) g : (8-10) mL : (1.023-1.265) g, the reaction temperature is 72-80℃, and the reaction time is 6-8 h; in step S3, the ratio of product b, m-diphenylacetonitrile, potassium carbonate, and N-bromosuccinimide is (0.934-1.125) g : (0.882-0.954) g : (0.122-0.147) g : (0.047-0.061) g, and the reaction is stirred for 4-6 h.

[0017] Preferably, in step one, the sheet thickness is 1-5 mm, and during the vacuum pressure impregnation process, the vacuum degree is 95-98%, the pressure is 2-3 MPa, and the time is 2-4 h; in step two, the ratio of expanded perlite, magnesium chloride aqueous solution, magnesium oxide, sodium phosphate, lithopone, emulsifier, and adhesive is (10-20) kg: (25-40) kg: (10-25) kg: (100-300) kg: (150-350) kg: (1-2.4) kg: (50-100) kg; the ratio of tetrahydrofuran, composite polymer, composite flame retardant, and perlite is (10-50) kg: (2-8) kg: (2-8) kg: (30-60) kg; in step three, the ratio of inorganic flame retardant slurry to organic adhesive is (75-90) kg: (10-25) kg.

[0018] A modified multilayer perlite composite flame-retardant board is prepared using the method described above.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention applies the prepared composite flame retardant and composite polymer to the composite flame retardant board system, which can not only improve its flame retardant performance and water and moisture resistance, but also improve its strength.

[0020] 2. The present invention introduces the obtained composite flame retardant into the multilayer perlite composite flame retardant board system, which can effectively improve its flame retardant performance and water and moisture resistance. When heated, the composite flame retardant promotes the condensation of the char phase, forming a dense char layer as a thermal and mass barrier. It works synergistically with the inorganic components, the inorganic phase constructs the refractory skeleton, the organic phase promotes char formation, and the carbonization products block the pores, weakening heat and mass transfer. The fluorine-containing groups can reduce the surface energy of the material, improve hydrophobic stability, and thus extend its service life.

[0021] 3. This invention applies the prepared composite polymer to the preparation process of multilayer perlite composite flame-retardant boards, which can effectively improve the impact resistance, water resistance, and flame retardancy of the composite flame-retardant boards. The aromatic structure, fluorine-containing structure, and amine addition segments contained in the composite polymer can improve the interfacial compatibility between the organic adhesive phase and expanded perlite, magnesium cementitious components, and wood surface layer, enhance the continuity of the core layer and the interlayer bonding strength, thereby improving the overall integrity, crack resistance, and impact resistance of the board. The fluorine-containing structure can reduce the surface energy of the material and weaken the wetting effect of moisture on the pore walls and interfaces of the core layer, thereby reducing the water absorption rate and improving the water resistance, moisture resistance, and dimensional stability of the board. The aromatic skeleton and polar functional groups are conducive to the formation of a relatively stable carbonized layer when heated, and have a synergistic effect with the perlite, phosphate, and magnesium inorganic flame-retardant system to construct a "organic carbonization-inorganic heat insulation" dual flame-retardant barrier, thereby delaying heat transfer and the release of combustible volatiles and improving the flame retardancy of the board. Detailed Implementation

[0022] 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.

[0023] Example 1: This example discloses a method for preparing a composite flame retardant, including the following steps: Q1: 1.941g of 4-(trifluoromethyl)phenylhydrazine, 1.271g of 3,4-difluoroacetophenone and 10g of polyphosphoric acid were added to a container, heated to 110℃ and stirred for 6h, then cooled. The pH was adjusted to 7 with 1mol / L sodium hydroxide aqueous solution. The aqueous phase was extracted with ethyl acetate, and the extract was dried with anhydrous sodium sulfate. The extract was purified by rotary evaporation to obtain organic compound 1. Q2: Add 0.904g of organic compound 1 and 0.515g of 4-dimethylaminopyridine to 10mL of dichloromethane, stir to dissolve, add 0.158g of triethylamine and 0.252g of methacryloyl chloride in an ice bath at 0℃, heat to 28℃ and stir for 3 days, add 5mL of dichloromethane to dilute, then quench with saturated ammonium chloride aqueous solution, extract the aqueous phase with dichloromethane, wash the organic layer with saturated ammonium chloride, dry with anhydrous sodium sulfate, filter, concentrate, purify, recrystallize to obtain organic compound 2; Q3: Add 0.279g of organic compound 2, 0.128g of dimethyl fluoromalonate, 0.353g of potassium carbonate and 3mL of acetonitrile to a container, stir and react for 2 hours, then quench with distilled water, extract with dichloromethane, dry with anhydrous sodium sulfate, filter, concentrate and purify to obtain a composite flame retardant.

[0024] This embodiment discloses a method for preparing a composite polymer, including the following steps: S1: 1.073 g of tetrafluoroterephthalic acid and 1.289 g of epichlorohydrin were added to a container and stirred at 60 °C for 30 min. Then, 0.08 g of sulfuric acid with a volume fraction of 98 vt% was added. The temperature was raised to 80 °C and stirred for 8 h. Then, 1.555 g of sodium hydroxide aqueous solution with a concentration of 1 mol / L was added and the reaction was stirred. After the reaction was completed, the product was extracted, allowed to stand, washed, and the oil phase was distilled under reduced pressure to obtain product a. S2: 1.224 g of 1,8-octanediamine was added to a container containing 9 mL of ethanol, followed by 1.144 g of product a. After mixing well, the mixture was heated to 80 °C and reacted for 6 h. After the reaction was completed, the product b was obtained by vacuum distillation. S3: 0.996g of product b, 0.914g of m-diphenylacetonitrile, 0.134g of potassium carbonate and 0.052g of N-bromosuccinimide were added sequentially to a container. After stirring and reacting for 6 hours, distilled water was added, and the mixture was distilled under reduced pressure, filtered, washed and dried to obtain the composite polymer.

[0025] This embodiment discloses a method for preparing a modified multilayer perlite composite flame-retardant board, including the following steps: Step 1: Process the wood into thin slices with a thickness of 1-5mm, then use a composite flame retardant and borax preservative to perform vacuum pressure impregnation treatment on the thin slices (vacuum degree of 97%, pressure of 2.5MPa, time of 3h), dry, splice, and obtain the wood surface layer; Step 2: Mix 15 kg of expanded perlite, 32 kg of 20 wt% magnesium chloride aqueous solution, 17 kg of magnesium oxide, 200 kg of sodium phosphate, 250 kg of lithopone, 1.7 kg of Span 60 and 75 kg of binder 750 to obtain an inorganic flame retardant slurry; mix 30 kg of tetrahydrofuran, 5 kg of composite polymer, 5 kg of composite flame retardant and 45 kg of perlite to obtain an organic adhesive. Step 3: Mix 80kg of inorganic flame retardant slurry and 20kg of organic adhesive to obtain flame retardant slurry; then add the flame retardant slurry into the mold and press it to obtain the flame retardant core layer board; Step 4: Assemble the wood surface layer and the flame-retardant core layer in an alternating manner, apply adhesive 750 between the layers to form a multi-layer composite board blank, press, cure, dry, and post-process to obtain the modified multi-layer perlite composite flame-retardant board.

[0026] Example 2: This example discloses a method for preparing a composite flame retardant, including the following steps: Q1: 1.852 g of 4-(trifluoromethyl)phenylhydrazine, 1.024 g of 3,4-difluoroacetophenone and 11 g of polyphosphoric acid were added to a container, heated to 110 °C and stirred for 6 h, then cooled. The pH was adjusted to 7 with 1 mol / L sodium hydroxide aqueous solution. The aqueous phase was extracted with ethyl acetate, and the extract was dried with anhydrous sodium sulfate. The extract was purified by rotary evaporation to obtain organic compound 1. Q2: Add 0.842g of organic compound 1 and 0.464g of 4-dimethylaminopyridine to 10mL of dichloromethane, stir to dissolve, add 0.114g of triethylamine and 0.225g of methacryloyl chloride in an ice bath at 0℃, heat to 28℃ and stir for 3 days, add 5mL of dichloromethane to dilute, then quench with saturated ammonium chloride aqueous solution, extract the aqueous phase with dichloromethane, wash the organic layer with saturated ammonium chloride, dry with anhydrous sodium sulfate, filter, concentrate, purify, recrystallize to obtain organic compound 2; Q3: Add 0.232g of organic compound 2, 0.115g of dimethyl fluoromalonate, 0.326g of potassium carbonate and 2mL of acetonitrile to a container, stir and react for 2 hours, then quench with distilled water, extract with dichloromethane, dry with anhydrous sodium sulfate, filter, concentrate and purify to obtain a composite flame retardant.

[0027] This embodiment discloses a method for preparing a composite polymer, including the following steps: S1: 1.022 g of tetrafluoroterephthalic acid and 1.225 g of epichlorohydrin were added to a container and stirred at 60 °C for 30 min. Then, 0.11 g of sulfuric acid with a volume fraction of 98 vt% was added. The temperature was raised to 80 °C and stirred for 8 h. Then, 1.453 g of sodium hydroxide aqueous solution with a concentration of 1 mol / L was added and the reaction was stirred. After the reaction was completed, the product was extracted, allowed to stand, washed, and the oil phase was distilled under reduced pressure to obtain product a. S2: 1.122 g of 1,8-octanediamine was added to a container containing 10 mL of ethanol, followed by 1.023 g of product a. After mixing thoroughly, the mixture was heated to 80 °C and reacted for 6 h. After the reaction was completed, the product b was obtained by vacuum distillation. S3: 0.934g of product b, 0.882g of m-diphenylacetonitrile, 0.122g of potassium carbonate and 0.047g of N-bromosuccinimide were added sequentially to a container. After stirring and reacting for 6 hours, distilled water was added, and the mixture was distilled under reduced pressure, filtered, washed and dried to obtain the composite polymer.

[0028] This embodiment discloses a method for preparing a modified multilayer perlite composite flame-retardant board, including the following steps: Step 1: Process the wood into thin slices with a thickness of 1-5mm, then use a composite flame retardant and boric acid preservative to perform vacuum pressure impregnation treatment on the thin slices (vacuum degree of 97%, pressure of 2.5MPa, time of 3h), dry, splice, and obtain the wood surface layer; Step 2: Mix 10 kg of expanded perlite, 25 kg of 20 wt% magnesium chloride aqueous solution, 10 kg of magnesium oxide, 300 kg of sodium phosphate, 350 kg of lithopone, 2.4 kg of Tween 60, and 50 kg of binder 802 to obtain an inorganic flame retardant slurry; mix 10 kg of tetrahydrofuran, 8 kg of composite polymer, 8 kg of composite flame retardant, and 30 kg of perlite to obtain an organic adhesive. Step 3: Mix 90kg of inorganic flame retardant slurry and 10kg of organic adhesive to obtain flame retardant slurry; then add the flame retardant slurry into the mold and press it to obtain flame retardant core board; Step 4: Assemble the wood surface layer and the flame-retardant core layer in an alternating manner, apply adhesive 802 between the layers to form a multi-layer composite board blank, press, cure, dry, and post-process to obtain the modified multi-layer perlite composite flame-retardant board.

[0029] Example 3: This example discloses a method for preparing a composite flame retardant, including the following steps: Q1: 2.022 g of 4-(trifluoromethyl)phenylhydrazine, 1.406 g of 3,4-difluoroacetophenone and 9 g of polyphosphoric acid were added to a container, heated to 110 °C and stirred for 6 h, then cooled. The pH was adjusted to 7 with 1 mol / L sodium hydroxide aqueous solution. The aqueous phase was extracted with ethyl acetate, and the extract was dried with anhydrous sodium sulfate. The extract was purified by rotary evaporation to obtain organic compound 1. Q2: Add 0.967g of organic compound 1 and 0.652g of 4-dimethylaminopyridine to 10mL of dichloromethane, stir to dissolve, add 0.205g of triethylamine and 0.294g of methacryloyl chloride in an ice bath at 0℃, heat to 28℃ and stir for 3 days, add 5mL of dichloromethane to dilute, then quench with saturated ammonium chloride aqueous solution, extract the aqueous phase with dichloromethane, wash the organic layer with saturated ammonium chloride, dry with anhydrous sodium sulfate, filter, concentrate, purify, recrystallize to obtain organic compound 2; Q3: Add 0.357g of organic compound 2, 0.148g of dimethyl fluoromalonate, 0.381g of potassium carbonate and 4mL of acetonitrile to a container, stir and react for 2 hours, then quench with distilled water, extract with dichloromethane, dry with anhydrous sodium sulfate, filter, concentrate and purify to obtain a composite flame retardant.

[0030] This embodiment discloses a method for preparing a composite polymer, including the following steps: S1: 1.147 g of tetrafluoroterephthalic acid and 1.369 g of epichlorohydrin were added to a container and stirred at 60 °C for 30 min. Then, 0.06 g of sulfuric acid with a volume fraction of 98 vt% was added. The temperature was raised to 80 °C and stirred for 8 h. Then, 1.658 g of sodium hydroxide aqueous solution with a concentration of 1 mol / L was added and the reaction was stirred. After the reaction was completed, the product was extracted, allowed to stand, washed, and the oil phase was distilled under reduced pressure to obtain product a. S2: 1.326 g of 1,8-octanediamine was added to a container containing 8 mL of ethanol, followed by 1.265 g of product a. After mixing evenly, the mixture was heated to 80 °C and reacted for 6 h. After the reaction was completed, the product b was obtained by vacuum distillation. S3: 1.125g of product b, 0.954g of m-diphenylacetonitrile, 0.147g of potassium carbonate and 0.061g of N-bromosuccinimide were added sequentially to a container. After stirring and reacting for 6 hours, distilled water was added, and the mixture was distilled under reduced pressure, filtered, washed and dried to obtain the composite polymer.

[0031] This embodiment discloses a method for preparing a modified multilayer perlite composite flame-retardant board, including the following steps: Step 1: Process the wood into thin slices with a thickness of 1-5mm, then use a composite flame retardant and disodium octaborate tetrahydrate preservative to perform vacuum pressure impregnation treatment on the thin slices (vacuum degree of 97%, pressure of 2.5MPa, time of 3h), dry, splice, and obtain the wood surface layer. Step 2: Mix 20 kg of expanded perlite, 40 kg of 20 wt% magnesium chloride aqueous solution, 25 kg of magnesium oxide, 100 kg of sodium phosphate, 150 kg of lithopone, 1 kg of alkali-resistant TRC flexible acrylic emulsion, and 100 kg of adhesive 707 to obtain an inorganic flame-retardant slurry; mix 50 kg of tetrahydrofuran, 2 kg of composite polymer, 2 kg of composite flame retardant, and 60 kg of perlite to obtain an organic adhesive. Step 3: Mix 75kg of inorganic flame retardant slurry and 25kg of organic adhesive to obtain flame retardant slurry; then add the flame retardant slurry into the mold and press it to obtain the flame retardant core layer board; Step 4: Assemble the wood surface layer and the flame-retardant core layer in an alternating manner, apply adhesive 707 between the layers to form a multi-layer composite board blank, press, cure, dry, and post-process to obtain the modified multi-layer perlite composite flame-retardant board.

[0032] Example 4: This example discloses a method for preparing a composite flame retardant, including the following steps: Q1: 1.893g of 4-(trifluoromethyl)phenylhydrazine, 1.128g of 3,4-difluoroacetophenone and 9.5g of polyphosphoric acid were added to a container, heated to 110℃ and stirred for 6h, then cooled. The pH was adjusted to 7 with 1mol / L sodium hydroxide aqueous solution. The aqueous phase was extracted with ethyl acetate, and the extract was dried with anhydrous sodium sulfate. The extract was purified by rotary evaporation to obtain organic compound 1. Q2: Add 0.868g of organic compound 1 and 0.488g of 4-dimethylaminopyridine to 10mL of dichloromethane, stir to dissolve, add 0.138g of triethylamine and 0.238g of methacryloyl chloride in an ice bath at 0℃, heat to 28℃ and stir for 3 days, add 5mL of dichloromethane to dilute, then quench with saturated ammonium chloride aqueous solution, extract the aqueous phase with dichloromethane, wash the organic layer with saturated ammonium chloride, dry with anhydrous sodium sulfate, filter, concentrate, purify, recrystallize to obtain organic compound 2; Q3: Add 0.261g of organic compound 2, 0.119g of dimethyl fluoromalonate, 0.343g of potassium carbonate and 2.5mL of acetonitrile to a container, stir and react for 2 hours, then quench with distilled water, extract with dichloromethane, dry with anhydrous sodium sulfate, filter, concentrate and purify to obtain a composite flame retardant.

[0033] This embodiment discloses a method for preparing a composite polymer, including the following steps: S1: 1.058 g of tetrafluoroterephthalic acid and 1.332 g of epichlorohydrin were added to a container and stirred at 60 °C for 30 min. Then, 0.07 g of sulfuric acid with a volume fraction of 98 vt% was added. The temperature was raised to 80 °C and stirred for 8 h. Then, 1.493 g of sodium hydroxide aqueous solution with a concentration of 1 mol / L was added and the reaction was stirred. After the reaction was completed, the product was extracted, allowed to stand, washed, and the oil phase was distilled under reduced pressure to obtain product a. S2: 1.186 g of 1,8-octanediamine was added to a container containing 8.5 mL of ethanol, followed by 1.087 g of product a. After mixing thoroughly, the mixture was heated to 80 °C and reacted for 6 h. After the reaction was completed, the product b was obtained by vacuum distillation. S3: 1.089g of product b, 0.931g of m-diphenylacetonitrile, 0.138g of potassium carbonate and 0.049g of N-bromosuccinimide were added sequentially to a container. After stirring and reacting for 6 hours, distilled water was added, and the mixture was distilled under reduced pressure, filtered, washed, and dried to obtain the composite polymer.

[0034] This embodiment discloses a method for preparing a modified multilayer perlite composite flame-retardant board, including the following steps: Step 1: Process the wood into thin slices with a thickness of 1-5mm, then use a composite flame retardant and boric acid preservative to perform vacuum pressure impregnation treatment on the thin slices (vacuum degree of 97%, pressure of 2.5MPa, time of 3h), dry, splice, and obtain the wood surface layer; Step 2: Mix 12 kg of expanded perlite, 28 kg of 20 wt% magnesium chloride aqueous solution, 12 kg of magnesium oxide, 150 kg of sodium phosphate, 200 kg of lithopone, 1.2 kg of Tween 60, and 60 kg of binder FD to obtain an inorganic flame retardant slurry; mix 25 kg of tetrahydrofuran, 4 kg of composite polymer, 6 kg of composite flame retardant, and 40 kg of perlite to obtain an organic adhesive. Step 3: Mix 85kg of inorganic flame retardant slurry and 15kg of organic adhesive to obtain flame retardant slurry; then add the flame retardant slurry into the mold and press to obtain flame retardant core board; Step 4: Assemble the wood surface layer and the flame-retardant core layer in an alternating manner, apply adhesive FD between the layers to form a multi-layer composite board blank, press, cure, dry, and post-process to obtain the modified multi-layer perlite composite flame-retardant board.

[0035] Example 5: This example discloses a method for preparing a composite flame retardant, including the following steps: Q1: 1.967 g of 4-(trifluoromethyl)phenylhydrazine, 1.331 g of 3,4-difluoroacetophenone and 10.5 g of polyphosphoric acid were added to a container, heated to 110 °C and stirred for 6 h. After cooling, the pH was adjusted to 7 with 1 mol / L sodium hydroxide aqueous solution. The aqueous phase was extracted with ethyl acetate, and the extract was dried with anhydrous sodium sulfate. The extract was purified by rotary evaporation to obtain organic compound 1. Q2: Add 0.933g of organic compound 1 and 0.613g of 4-dimethylaminopyridine to 10mL of dichloromethane, stir to dissolve, add 0.191g of triethylamine and 0.271g of methacryloyl chloride in an ice bath at 0℃, heat to 28℃ and stir for 3 days, add 5mL of dichloromethane to dilute, then quench with saturated ammonium chloride aqueous solution, extract the aqueous phase with dichloromethane, wash the organic layer with saturated ammonium chloride, dry with anhydrous sodium sulfate, filter, concentrate, purify, recrystallize to obtain organic compound 2; Q3: Add 0.317g of organic compound 2, 0.136g of dimethyl fluoromalonate, 0.369g of potassium carbonate and 3.5mL of acetonitrile to a container, stir and react for 2 hours, then quench with distilled water, extract with dichloromethane, dry with anhydrous sodium sulfate, filter, concentrate and purify to obtain the composite flame retardant.

[0036] This embodiment discloses a method for preparing a composite polymer, including the following steps: S1: 1.116 g of tetrafluoroterephthalic acid and 1.271 g of epichlorohydrin were added to a container and stirred at 60 °C for 30 min. Then, 0.09 g of sulfuric acid with a volume fraction of 98 vt% was added. The temperature was raised to 80 °C and stirred for 8 h. Then, 1.602 g of sodium hydroxide aqueous solution with a concentration of 1 mol / L was added and the reaction was stirred. After the reaction was completed, the product was extracted, allowed to stand, washed, and the oil phase was distilled under reduced pressure to obtain product a. S2: 1.304 g of 1,8-octanediamine was added to a container containing 9.5 mL of ethanol, followed by 1.196 g of product a. After mixing thoroughly, the mixture was heated to 80 °C and reacted for 6 h. After the reaction was completed, the product b was obtained by vacuum distillation. S3: 0.971g of product b, 0.898g of m-diphenylacetonitrile, 0.142g of potassium carbonate and 0.058g of N-bromosuccinimide were added sequentially to a container. After stirring and reacting for 6 hours, distilled water was added, and the mixture was distilled under reduced pressure, filtered, washed and dried to obtain the composite polymer.

[0037] This embodiment discloses a method for preparing a modified multilayer perlite composite flame-retardant board, including the following steps: Step 1: Process the wood into thin slices with a thickness of 1-5mm, then use a composite flame retardant and borax preservative to perform vacuum pressure impregnation treatment on the thin slices (vacuum degree of 97%, pressure of 2.5MPa, time of 3h), dry, splice, and obtain the wood surface layer; Step 2: Mix 18 kg of expanded perlite, 36 kg of 20 wt% magnesium chloride aqueous solution, 21 kg of magnesium oxide, 250 kg of sodium phosphate, 300 kg of lithopone, 2.2 kg of Span 60 and 80 kg of binder BH to obtain an inorganic flame retardant slurry; mix 45 kg of tetrahydrofuran, 6 kg of composite polymer, 4 kg of composite flame retardant and 50 kg of perlite to obtain an organic adhesive. Step 3: Mix 88kg of inorganic flame retardant slurry and 12kg of organic adhesive to obtain flame retardant slurry; then add the flame retardant slurry into the mold and press it to obtain the flame retardant core layer board; Step 4: Assemble the wood surface layer and the flame-retardant core layer in an alternating manner, apply adhesive BH between the layers to form a multi-layer composite board blank, press, cure, dry, and post-process to obtain the modified multi-layer perlite composite flame-retardant board.

[0038] Comparative Example 1: Compared with Example 1, Comparative Example 1 did not add composite polymer during the preparation of composite flame retardant board, and all other conditions remained unchanged.

[0039] Comparative Example 2: Compared with Example 1, Comparative Example 2 did not add composite flame retardant during the preparation of composite flame retardant board, and all other conditions remained unchanged.

[0040] Performance testing: The composite flame-retardant boards prepared according to Examples 1-5 and Comparative Examples 1-2 were subjected to performance tests. The combustion performance of the samples was tested according to GB8624-2012, and the water resistance and impact resistance of the samples were tested according to GB / T 17657-2022. The test results are shown in Table 1. Table 1 Example 1 B1 6.73 852.5 Example 2 B1 6.86 848.2 Example 3 B1 6.88 846.9 Example 4 B1 6.79 849.4 Example 5 B1 6.81 847.7 Comparative Example 1 B1 13.6 656.8 Comparative Example 2 B2 14.7 764.7 According to the test results in Table 1, the present invention significantly improves the overall performance of the multilayer perlite composite flame-retardant board system by applying the prepared composite flame retardant and composite polymer. Examples 1-5 all achieved a B1 flammability rating, demonstrating excellent flame retardancy and low water absorption. The ball drop height was approximately 852.5 mm, indicating excellent impact resistance. Comparing Comparative Example 1 with Examples 1-5, without the addition of the composite polymer, the flammability rating remained B1, but the 24-hour water absorption increased to approximately 13.6%, and the ball drop height decreased to approximately 656 mm, indicating increased interfacial brittleness and decreased water and moisture resistance. Comparative Example 2, without the addition of the composite flame retardant, had a flammability rating reduced to B2, a 24-hour water absorption increased to approximately 14.7%, and a ball drop height of approximately 764 mm, indicating decreased flame retardancy and poor water and moisture resistance.

[0041] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0042] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a modified multilayer perlite composite flame-retardant board, characterized in that, Includes the following steps: Step 1: Process the wood into thin slices, then use a composite flame retardant and preservative to impregnate the slices under vacuum pressure, dry them, and splice them together to obtain the wood surface layer; Step 2: Mix expanded perlite, magnesium chloride aqueous solution, magnesium oxide, sodium phosphate, lithopone, emulsifier and binder to obtain inorganic flame retardant slurry; mix tetrahydrofuran, composite polymer, composite flame retardant and perlite to obtain organic adhesive material; Step 3: Mix the inorganic flame retardant slurry and the organic adhesive to obtain the flame retardant slurry; then add the flame retardant slurry into the mold and press it to obtain the flame retardant core layer board; Step 4: Assemble the wood surface layer and the flame-retardant core layer in an alternating manner, apply adhesive between the layers to form a multi-layer composite board blank, press, cure, dry, and post-process to obtain the modified multi-layer perlite composite flame-retardant board.

2. The method for preparing a modified multilayer perlite composite flame-retardant board according to claim 1, characterized in that, The preparation method of the composite flame retardant, Includes the following steps: Q1: Add 4-(trifluoromethyl)phenylhydrazine, 3,4-difluoroacetophenone and polyphosphoric acid to a container, heat and stir to mix, cool, adjust pH, extract the aqueous phase with ethyl acetate, dry the extract, rotary evaporate, and purify to obtain organic compound 1; Q2: Organic compound 1 and 4-dimethylaminopyridine were added to dichloromethane and stirred to dissolve. Triethylamine and methacryloyl chloride were added under ice bath conditions. After heating and stirring, dichloromethane was added to dilute the mixture. The solution was then quenched with saturated ammonium chloride solution. The aqueous phase was extracted with dichloromethane, and the organic layer was washed with saturated ammonium chloride. The mixture was dried, filtered, concentrated, purified, and recrystallized to obtain organic compound 2. Q3: Add organic compound 2, dimethyl fluoromalonate, potassium carbonate and acetonitrile to a container, stir and react, then quench with distilled water, extract with dichloromethane, dry, filter, concentrate and purify to obtain a composite flame retardant.

3. The method for preparing a modified multilayer perlite composite flame-retardant board according to claim 2, characterized in that, In Q1, the ratio of 4-(trifluoromethyl)phenylhydrazine, 3,4-difluoroacetophenone and polyphosphoric acid is (1.852-2.022) g : (1.024-1.406) g : (9-11) g.

4. The method for preparing a modified multilayer perlite composite flame-retardant board according to claim 2, characterized in that, In Q2, the ratio of organic compounds 1,4-dimethylaminopyridine, triethylamine and methacryloyl chloride is (0.842-0.967) g : (0.464-0.652) g : (0.114-0.205) g : (0.225-0.294) g.

5. The method for preparing a modified multilayer perlite composite flame-retardant board according to claim 2, characterized in that, In Q3, the ratio of organic compound 2, dimethyl fluoromalonate, potassium carbonate and acetonitrile is (0.232-0.357) g : (0.115-0.148) g : (0.326-0.381) g : (2-4) mL.

6. The method for preparing a modified multilayer perlite composite flame-retardant board according to claim 1, characterized in that, The method for preparing the composite polymer includes the following steps: S1: Tetrafluoroterephthalic acid and epichlorohydrin were added to a container, heated and stirred to react, sulfuric acid was added, and the reaction was continued to be heated and stirred. Sodium hydroxide aqueous solution was added and the reaction was continued to be stirred. After the reaction was completed, the product was extracted, allowed to stand, washed, and the oil phase was distilled under reduced pressure to obtain product a. S2: Add 1,8-octanediamine to a container containing ethanol, then add product a, mix well, heat to react, and after the reaction is complete, distill under reduced pressure to obtain product b; S3: Product b, m-diphenylacetonitrile, potassium carbonate and N-bromosuccinimide were added to a container in sequence, stirred and reacted, then distilled water was added, the mixture was distilled under reduced pressure, filtered, washed and dried to obtain the composite polymer.

7. The method for preparing a modified multilayer perlite composite flame-retardant board according to claim 6, characterized in that, In S1, the ratio of tetrafluoroterephthalic acid, epichlorohydrin, sulfuric acid and sodium hydroxide aqueous solution is (1.022-1.147) g : (1.225-1.369) g : (0.06-0.11) g : (1.453-1.658) g.

8. The method for preparing a modified multilayer perlite composite flame-retardant board according to claim 6, characterized in that, In S2, the ratio of 1,8-octanediamine, ethanol, and product a is (1.122-1.326) g : (8-10) mL : (1.023-1.265) g; in S3, the ratio of product b, m-diphenylacetonitrile, potassium carbonate, and N-bromosuccinimide is (0.934-1.125) g : (0.882-0.954) g : (0.122-0.147) g : (0.047-0.061) g.

9. The method for preparing a modified multilayer perlite composite flame-retardant board according to claim 1, characterized in that, In step two, the ratio of expanded perlite, magnesium chloride aqueous solution, magnesium oxide, sodium phosphate, lithopone, emulsifier and adhesive is (10-20) kg: (25-40) kg: (10-25) kg: (100-300) kg: (150-350) kg: (1-2.4) kg: (50-100) kg; the ratio of tetrahydrofuran, composite polymer, composite flame retardant and perlite is (10-50) kg: (2-8) kg: (2-8) kg: (30-60) kg; in step three, the ratio of inorganic flame retardant slurry and organic adhesive is (75-90) kg: (10-25) kg.

10. A modified multilayer perlite composite flame-retardant board, characterized in that, It is prepared by the method described in any one of claims 1-9.

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