A non-formaldehyde-releasing flame-retardant bio-based material and a method for preparing the same

Abstract

The application discloses a kind of non-formaldehyde release difficultly burning biological matrix and preparation method thereof, belong to environmental protection artificial board technical field.The application uses silane coupling agent modified biomass and halogen-free flame retardant as raw material, using the system of multiple functionality polyurethane acrylate and polythiol through thiol-alkene click chemistry reaction solidification as adhesive.The application realizes the firm combination and uniform dispersion of each component in the board through the combination of interface modification and advanced adhesive system, so as to prepare a kind of completely non-formaldehyde release, excellent flame-retardant performance, good water resistance green composite.The application controllable process, raw material renewable, provide an effective solution for the preparation of high-performance environmental protection flame-retardant board.

Description

Technical Field

[0001] This invention belongs to the field of environmentally friendly artificial board technology, specifically relating to a formaldehyde-free, flame-retardant biomaterial and its preparation method. Background Technology

[0002] Bio-based materials are a type of board made from low-value straw, reeds, and other raw materials, and are in high demand in industries such as building decoration, furniture manufacturing, and more. Currently, most mainstream bio-based materials on the market use urea-formaldehyde resin, phenol-formaldehyde resin, and other "three-aldehyde adhesives" as binders. These adhesives continuously release formaldehyde during production and use, seriously endangering human health. Furthermore, boards made primarily from wood or agricultural residues are inherently flammable, posing a significant fire hazard. Therefore, developing formaldehyde-free, highly flame-retardant, and environmentally friendly bio-based materials has become an urgent need for the industry.

[0003] In existing technologies, researchers have explored various approaches to achieve formaldehyde-free and flame-retardant properties. For example, Chinese patent CN118927364A discloses a process that uses silicon-containing corn stalk shavings, nitrogen-containing corn starch adhesive, and boron-containing additives to achieve flame retardancy through boron-silicon-nitrogen synergy. However, the corn starch adhesive used in this technology still has limitations in terms of water resistance, bonding strength, and curing speed. Another existing technology, "Preparation and Application Research of Formaldehyde-Free Soybean Protein-Based Flame-Retardant Adhesive" (Pang Lin, 2016), uses alkali-modified soybean protein adhesive combined with a self-made inorganic flame retardant (such as zinc borate), which has good flame-retardant effects, but the water resistance and bonding strength of the protein adhesive are generally lower than those of synthetic resin adhesives.

[0004] Thiol-olefin click chemistry is a major type of carbon-carbon multi-bond addition reaction, possessing advantages such as stereoselectivity and high yield. It can be carried out under ultraviolet light or thermal initiation and is commonly used in the synthesis of dendritic polymers and surface modification of materials, with numerous applications in materials and biomedical sciences. Through thiol-olefin click chemistry, rapid curing can be achieved under mild conditions, forming a highly cross-linked network structure. Polyurethane acrylate (PUA) adhesives containing multiple reactive double bonds offer advantages such as rapid curing, high bond strength, and good water resistance. Combining this advanced adhesive system with bio-based materials and highly efficient flame retardants holds promise for preparing boards with excellent overall performance. However, ensuring the uniform dispersion of flame retardants (such as ammonium polyphosphate APP) in a hydrophobic reactive resin system and guaranteeing good interfacial bonding with biomass substrates (such as straw and reeds) remains a technical challenge. Direct mechanical mixing easily leads to flame retardant agglomeration, affecting the mechanical properties and flame retardant uniformity of the boards.

[0005] Therefore, there is an urgent need for a new technical solution that can organically combine high-performance reactive adhesives, high-efficiency flame retardants and biomass substrates, so as to endow the boards with excellent flame retardant and physical and mechanical properties while ensuring formaldehyde-free and environmentally friendly characteristics. Summary of the Invention

[0006] To address the problems of insufficient bonding strength or flame retardant properties of existing engineered wood products, poor compatibility between flame retardants and adhesives, and formaldehyde release, this invention provides a formaldehyde-free flame-retardant bio-based material and its preparation method.

[0007] The formaldehyde-free, flame-retardant biomaterial of this invention has the following formulation by weight parts:

[0008] 70-90 parts of silane coupling agent modified biomass substrate, 5-15 parts of silane coupling agent modified flame retardant, 5-15 parts of compound adhesive, and 1-2 parts of thermal initiator.

[0009] The silane coupling agent modified biomass substrate is obtained by modifying the biomass substrate with a silane coupling agent. Specifically, the biomass substrate is pulverized to a size of 100 mesh, then mixed with a silane coupling agent and water at 50-90°C for 5-20 minutes for modification. After drying, the silane coupling agent modified biomass substrate is obtained. The mass ratio of biomass substrate, silane coupling agent, and water is 90:5:5.

[0010] The biomass substrate is selected from one or more of reeds, straw, rice husks, sugarcane bagasse, corn stalks, sawdust, bamboo shavings, flax, and miscanthus, mixed in any proportion.

[0011] The silane coupling agent modified flame retardant is obtained by modifying a flame retardant with a silane coupling agent. Specifically, the flame retardant, silane coupling agent, and water are mixed at 50-90°C for 5-20 minutes for modification, and then dried to obtain the silane coupling agent modified flame retardant (FR@Si). The mass ratio of flame retardant, silane coupling agent, and water is 90:5:5.

[0012] The flame retardant is selected from one or more of the following: ammonium polyphosphate, piperazine pyrophosphate, magnesium hydroxide, aluminum hydroxide, hydrotalcite, melamine phosphate, melamine polyphosphate, melamine cyanurate, pentaerythritol, triazine charring agent CFA, aluminum hypophosphite, aluminum phosphonate, expandable graphite, zinc borate, sodium metaborate, graphene, transition metal disulfides, carbon nanotubes, halloysite, sepiolite, kaolin, and polyborosiloxane, mixed in any proportion.

[0013] The silane coupling agent is selected from one or more of the following: methacryloxypropyltrimethoxysilane (KH570), vinyltriethoxysilane (A151), vinyltrimethoxysilane (A171), vinyltri(β-methoxyethoxy)silane (A172), 3-mercaptopropyltriethoxysilane (KH580), 3-mercaptopropyltrimethoxysilane (KH590), and mercaptopropylmethyldimethoxysilane, mixed in any proportion.

[0014] The compound adhesive is composed of a multifunctional acrylate adhesive and a polythiol, wherein the polythiol accounts for 20%-40% by mass, and the remainder is the multifunctional acrylate adhesive.

[0015] Furthermore, the molar ratio of the thiol groups in the polythiols to the double bonds in the polyfunctional acrylate adhesives is controlled to be 1:1.

[0016] The multifunctional acrylate adhesive is selected from one or more of the following: hexafunctional polyurethane acrylate (PUA), EBECRYL 600, EBECRYL 745, EBECRYL 1290, EBECRYL 8210, EBECRYL 860, CN991, CN9012, and Cyracure® UVR-6105, as well as TAMPO containing -1P, PETAO containing +1P, DABP containing +3P, and TAEP containing +5P, mixed in any proportion. TAMPO, PETAO, DABP, and TAEP are prepared in-house, while the remaining raw materials are commercially available.

[0017] The preparation methods of TAMPO, PETAO, DABP and TAEP are as follows:

[0018] (a) Preparation of TAMPO containing -1 valent phosphorus

[0019] 0.1 mol of tris(hydroxymethyl)phosphine oxide (THPO), 0.35 mol of triethylamine (TEA), and 0.0648 g of 2,4-dimethyl-6-tert-butylphenol were added to a 500 mL round-bottom flask, followed by 300 mL of dichloromethane and stirred until homogeneous. The flask was then immersed in an ice bath, and 0.35 mol of acryloyl chloride (AC) was added dropwise. After the addition was complete, the reaction was allowed to proceed at room temperature for 12 h. After the reaction was complete, the mixture was washed three times with 1 M hydrochloric acid solution and once with saturated sodium bicarbonate solution. The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated to 70 mL. The solution was then passed through a 2 cm diameter, 6 cm long neutral alumina column, and the solvent was evaporated under vacuum at room temperature to obtain a slightly viscous, deep yellow liquid, namely TAMPO containing -1 valent phosphorus.

[0020] (b) Preparation of PETAO containing +1 valent phosphorus

[0021] 0.105 mol of pentaerythritol triacrylate (PETA) was added to 100 mL of dichloromethane and stirred to disperse. Then, 0.105 mol of triethylamine was added, and the mixture was stirred for 15 min under ice bath conditions to ensure uniform dispersion. 0.1 mol of diphenylphosphine chloride (DC) was slowly added dropwise using a separatory funnel, ensuring the addition was completed within 1 h. The reaction was maintained for 1 h, followed by continued reaction at room temperature for 12 h. After the reaction was completed, the mixture was filtered, and the lower layer was washed three times with deionized water. The lower layer was extracted, and the mixture was rotary evaporated under vacuum at 30 °C for 30 min to obtain PETAO containing +1 valent phosphorus.

[0022] (c) Preparation of DABP containing +3 valent phosphorus

[0023] 0.2 mol of 2-hydroxyethyl acrylate (HEA) was added to 100 mL of chloroform and stirred to disperse. Then, 0.3 mol of triethylamine was added, and the mixture was stirred for 15 min under ice bath conditions to ensure uniform dispersion. 0.12 mol of phenylphosphonodichlorophenyl BPOD was slowly added dropwise using a separatory funnel, completing the addition within 1 h. The reaction was maintained for 1 h, and then transferred to a 30 °C oil bath for 24 h. After the reaction was completed, the mixture was filtered, and the lower layer was washed three times with deionized water. The lower layer was extracted, and the mixture was rotary evaporated under vacuum at 45 °C for 30 min to obtain DABP containing +3 valent phosphorus.

[0024] (d) Preparation of TAEP containing +5 valent phosphorus

[0025] A solution of 0.305 mol hydroxyethyl acrylate (HEA) and 0.355 mol triethylamine in 100 mL of diethyl ether was added to a 250 mL round-bottom flask equipped with a calcium chloride drying tube and stirred until homogeneous. Under ice bath conditions, a mixture of 0.102 mol phosphorus oxychloride (POCl3) and 20 mL of diethyl ether was slowly added dropwise to the flask. After the addition was complete, the reaction was allowed to proceed at room temperature for 12 h. After the reaction was completed, the triethylcarbamate byproduct was removed by filtration. The resulting filtrate was extracted twice, successively with 1 M hydrochloric acid, 10% sodium bicarbonate solution, and saturated sodium chloride aqueous solution. The organic phase was dried over anhydrous sodium sulfate and then the solvent was removed under vacuum to obtain a colorless liquid product, namely TAEP containing +5 valent phosphorus.

[0026]

[0027] The polythiols are selected from one or more of 4,4'-dimercaptobiphenyl, 4,4'-dimercaptodiphenyl ether, trimercaptotriazine, 1,2,4,5-tetramercaptobenzene, trimethylolpropane tris(3-mercaptopropionate) (TMPMP), pentaerythritol tetra(mercaptoacetic acid) ester, and pentaerythritol tetra(3-mercaptopropionic acid) ester (PETMP), and are mixed in any proportion.

[0028] The thermal initiator is tert-butyl peroxyneodecanate (TBPD).

[0029] The present invention provides a method for preparing a formaldehyde-free, flame-retardant biomaterial, comprising the following steps:

[0030] Step 1: Dissolve the multifunctional acrylate adhesive, polythiol and thermal initiator in a low-boiling-point organic solvent and stir until homogeneous to obtain an adhesive solution.

[0031] The low-boiling-point organic solvent is selected from one or more of ethanol, ethyl acetate, acetone, tetrahydrofuran, cyclopentyl methyl ether, isopropanol, dichloromethane, and chloroform.

[0032] Step 2: Add the silane coupling agent modified biomass substrate and the silane coupling agent modified flame retardant FR@Si into a high-speed mixer according to the specified ratio. During the stirring process, spray the prepared adhesive solution evenly through a spray gun and continue stirring until the mixture is uniform to obtain the adhesive mixture.

[0033] Step 3: Lay the adhesive mixture into the mold, place it in a hot press and pre-press it at 60℃ for 1-2 minutes to evaporate the solvent, then raise the temperature to 150-170℃, press it to 3-5 MPa, and hold it at that temperature for 5-15 minutes to allow the thermal initiator to decompose completely and initiate deep curing of the resin; after depressurizing, cool the board to room temperature and demold it to obtain formaldehyde-free, flame-retardant, bio-based board.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. Superior Physical and Mechanical Properties: Compared to traditional double-bond thermosetting methods, the addition of multifunctional thiols in an equivalent amount to the double bonds transforms the curing mechanism into a stepwise growth polymerization dominated by thiols-ene click chemistry, eliminating the significant internal stress caused by adhesive shrinkage. This ensures a low-stress, high-strength interfacial bond between the adhesive, the silane coupling agent-modified reed fiber, and the flame retardant, which is crucial for achieving excellent internal bond strength and low warpage in the board.

[0036] 2. Improved production efficiency: This curing system is insensitive to oxygen in the air, overcoming the problem of surface oxygen inhibition in traditional acrylate free radical polymerization. It ensures that the surface and core layer are fully cured simultaneously during the laying and pre-pressing process, avoiding surface stickiness and improving process stability and product appearance quality.

[0037] 3. Completely formaldehyde-free: The main components of the base material, flame retardant, and adhesive used in this invention do not contain formaldehyde, and no formaldehyde is added during the preparation process, thus eliminating formaldehyde pollution at the source and making the product environmentally friendly and safe.

[0038] 4. Excellent flame retardant and smoke suppression properties: By modifying the flame retardant with a silane coupling agent, its compatibility with organic adhesives and its dispersion uniformity in the board are significantly improved, thus maximizing its flame retardant efficiency.

[0039] 5. Renewable raw materials, green and sustainable: The main base material is rapidly growing biomass resources. Although the adhesives and flame retardants are synthetic products, the overall solution reduces the dependence on fossil resources, which is in line with the development direction of green materials. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the synthesis route of the present invention. Detailed Implementation

[0041] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not intended to limit the scope of the present invention.

[0042] Example 1: Preparation of APP@Si flame-retardant reed substrate based on hexafunctional resin adhesive PUA

[0043] 1. Material Pretreatment: 90 parts of reed and 90 parts of ammonium polyphosphate (APP) were modified by mixing them separately in a mixed solvent containing 5 parts of silane coupling agent KH570 and 5 parts of water at 50°C for 20 minutes. After drying, reed LW@Si modified with silane coupling agent and flame retardant APP@Si modified with silane coupling agent were obtained. 0.016 mol (16 g) of hexafunctional polyurethane acrylate (PUA), 0.012 mol (5.19 g) of pentaerythritol tetra(thioglycolic acid) ester and 0.4 g of thermal initiator TBPD were dissolved in 60 ml of tetrahydrofuran and stirred evenly to obtain an adhesive solution.

[0044] 2. Mixing and applying adhesive: Add 80 parts of reed@Si and 10 parts of APP@Si to a high-speed mixer. During the mixing process, spray 10 parts of the prepared adhesive solution evenly through a spray gun. Continue mixing until the mixture is uniform to obtain the adhesive mixture.

[0045] 3. Curing: The adhesive mixture is laid in a 3-8mm mold and cured using a segmented heating process: First, the temperature is raised to 60℃ and held for 2 minutes; then the temperature is raised to 160℃, the pressure is increased to 3 MPa, and the pressure is held for 5 minutes; after depressurization, the board is cooled to room temperature and demolded to obtain APP@Si flame-retardant reed substrate LW-3 based on hexafunctional resin adhesive PUA.

[0046] By modifying the formulation components, straw-based materials (LW-1) and flame-retardant straw-based materials (LW-2) were prepared, with specific formulations shown in Table 1. LW-4 and LW-5 were prepared by replacing PUA with formaldehyde-containing urea-formaldehyde resin (UF) and phenolic resin (PF), respectively. Sample dimensions of the relevant materials are shown in Table 1, and test results are shown in Tables 2 and 3. Note that LW-1 and LW-2 could not be tested for vertical burning, oxygen index, and mechanical properties.

[0047]

[0048]

[0049]

[0050] Example 2: APP@Si flame-retardant straw substrate prepared based on EBECRYL 600

[0051] 1. Material Pretreatment: 90 parts of straw and 90 parts of ammonium polyphosphate (APP) were modified by mixing them separately with a mixed solvent of 5 parts silane coupling agent KH570 and 5 parts water at 70℃ for 10 minutes. After drying, straw@Si modified with silane coupling agent and flame retardant APP@Si modified with silane coupling agent were obtained. 0.02 mol EBECRYL 600, 0.03 mol trimethylolpropane tris(3-mercaptopropionate) (TMPMP) and 0.5 g thermal initiator TBPD were dissolved in 80 ml tetrahydrofuran and stirred evenly to obtain an adhesive solution.

[0052] 2. Mixing and applying adhesive: Put 70 parts of straw@Si and 15 parts of APP@Si into a high-speed mixer, and during the mixing process, spray 15 parts of the prepared adhesive solution evenly through a spray gun, and continue to mix until the mixture is uniform to obtain the adhesive mixture.

[0053] 3. Curing: The adhesive mixture is laid in a 3-8mm mold and cured using a segmented heating process: first, the temperature is raised to 65℃ and held for 1 minute; then the temperature is raised to 170℃, the pressure is increased to 5 MPa, and the pressure is held for 5 minutes; after depressurization, the board is cooled to room temperature and demolded to obtain the APP@Si flame-retardant straw substrate JG-3 prepared based on EBECRYL 600.

[0054] Other material formulations are listed in Table 4. Straw-based and flame-retardant straw-based materials were prepared using the same method. JG-4 and JG-5 were prepared by adding formaldehyde-containing urea-formaldehyde resin (UF) and phenolic resin (PF). Sample dimensions of the relevant materials are shown in Table 1, and test results are shown in Tables 4 and 5. Vertical burning, oxygen index, and mechanical property tests could not be performed on JG-1 and JG-2.

[0055]

[0056]

[0057] Example 3: PAPP@Si flame-retardant wood chip substrate prepared based on EBECRYL 600 and DABP

[0058] 1. Preparation of DABP: 0.2 mol of 2-hydroxyethyl acrylate (HEA) was added to 100 mL of chloroform and stirred to disperse. Then, 0.3 mol of triethylamine was added, and the mixture was stirred for 15 min under ice bath conditions to ensure uniform dispersion. 0.12 mol of phenylphosphonodichloro(BPOD) was slowly added dropwise using a separatory funnel, ensuring the addition was completed within 1 h. The reaction was maintained for 1 h, and then transferred to a 30 °C oil bath for 24 h. After the reaction was completed, the mixture was filtered, and the lower layer was washed three times with deionized water. The lower layer was extracted, and the mixture was rotary evaporated under vacuum at 45 °C for 30 min to obtain DABP containing +3 valent phosphorus.

[0059] 2. Material Pretreatment: 90 parts of sawdust and 90 parts of piperazine pyrophosphate (PAPP) were modified by mixing them separately with a mixed solvent of 5 parts 3-mercaptopropyltrimethoxysilane (KH590) and 5 parts water at 90°C for 5 minutes. After drying, straw@Si modified with silane coupling agent and flame retardant PAPP@Si modified with silane coupling agent were obtained. 0.02 mol EBECRYL 600 (or 0.02 mol DABP), 0.06 mol 4,4'-dimercaptobiphenyl and 0.8 g thermal initiator TBPD were dissolved in 100 ml tetrahydrofuran and stirred evenly to obtain an adhesive solution.

[0060] 3. Mixing and applying adhesive: Put 90 parts of wood chips@Si and 5 parts of PAPP@Si into a high-speed mixer. During the mixing process, spray 5 parts of the prepared adhesive solution evenly through a spray gun and continue mixing until the mixture is uniform to obtain the adhesive mixture.

[0061] 4. Curing: The adhesive mixture is laid in a 3-8mm mold. First, the temperature is raised to 55℃ and held for 2 minutes. Then, the temperature is raised to 150℃, the pressure is increased to 5 MPa, and the temperature is held for 5 minutes. After depressurization, the board is cooled to room temperature and demolded to obtain the PAPP@Si flame-retardant wood chip substrates MX-3 and MX-4 prepared based on EBECRYL 600 and DABP.

[0062] Other material formulations are listed in Table 6. Wood chip substrate and flame-retardant wood chip substrate were prepared using the same method. Formaldehyde-containing urea-formaldehyde resin (UF) and phenolic resin (PF) were added to prepare MX-5 and MX-6. Sample dimensions of related materials are shown in Table 1, and test results are shown in Tables 6 and 7. Vertical burning, oxygen index, and mechanical property tests could not be performed on MX-1 and MX-2.

[0063]

[0064]

[0065] Based on the above experimental results, the following conclusions can be drawn:

[0066] This invention achieves excellent compatibility and strong bonding between components by using a silane coupling agent to modify the surface of biomass substrates and flame retardants, and by innovatively applying a multifunctional acrylate adhesive system based on thiol-ene click chemistry. This invention not only achieves complete environmental friendliness (formaldehyde-free) for the boards, but also achieves synergistic optimization in core functionalities such as flame retardancy and mechanical properties. The prepared boards have broad application prospects in high-end interior decoration, environments with strict fire protection requirements, and green building.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A formaldehyde-free, flame-retardant biomaterial, characterized in that... Its formula, by mass parts, is as follows: 70-90 parts of silane coupling agent modified biomass substrate, 5-15 parts of silane coupling agent modified flame retardant, 5-15 parts of compound adhesive, and 1-2 parts of thermal initiator. The compound adhesive is composed of a polyfunctional acrylate adhesive and a polythiol. The polythiol accounts for 20%-40% of the mass of the compound adhesive, with the remainder being the polyfunctional acrylate adhesive. The molar ratio of the thiol groups in the polythiol to the double bonds in the polyfunctional acrylate adhesive is controlled to be 1:

1. The multifunctional acrylate adhesive is selected from one or more of the following: hexafunctional polyurethane acrylate, EBECRYL 600, EBECRYL 745, EBECRYL 1290, EBECRYL 8210, EBECRYL 860, CN991, CN9012, Cyracure® UVR-6105, TAMPO containing -1P, PETAO containing +1P, DABP containing +3P, and TAEP containing +5P, mixed in any proportion. The structures of TAMPO, PETAO, DABP, and TAEP are shown below: 。 2. The formaldehyde-free, flame-retardant biomaterial according to claim 1, characterized in that: The silane coupling agent modified biomass substrate is obtained by modifying the biomass substrate with a silane coupling agent; The biomass substrate is selected from one or more of reeds, straw, rice husks, sugarcane bagasse, corn stalks, sawdust, bamboo shavings, flax, and miscanthus, mixed in any proportion.

3. The formaldehyde-free, flame-retardant biomaterial according to claim 1, characterized in that: The silane coupling agent modified flame retardant is obtained by modifying the flame retardant with a silane coupling agent; The flame retardant is selected from one or more of the following: ammonium polyphosphate, piperazine pyrophosphate, magnesium hydroxide, aluminum hydroxide, hydrotalcite, melamine phosphate, melamine polyphosphate, melamine cyanurate, pentaerythritol, triazine charring agent CFA, aluminum hypophosphite, aluminum phosphonate, expandable graphite, zinc borate, sodium metaborate, graphene, transition metal disulfides, carbon nanotubes, halloysite, sepiolite, kaolin, and polyborosiloxane, mixed in any proportion.

4. The formaldehyde-free, flame-retardant biomaterial according to claim 2 or 3, characterized in that: The silane coupling agent is selected from one or more of methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, and mercaptopropylmethyldimethoxysilane, mixed in any proportion.

5. The formaldehyde-free, flame-retardant biomaterial according to claim 1, characterized in that: The polythiols are selected from one or more of 4,4'-dimercaptobiphenyl, 4,4'-dimercaptodiphenyl ether, trimercaptotriazine, 1,2,4,5-tetramercaptobenzene, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(mercaptoacetic acid) ester, and pentaerythritol tetra(3-mercaptopropionic acid) ester, mixed in any proportion.

6. A method for preparing the formaldehyde-free, flame-retardant biomaterial according to any one of claims 1-5, characterized in that... Includes the following steps: Step 1: Dissolve the multifunctional acrylate adhesive, polythiol and thermal initiator in a low-boiling-point organic solvent and stir until homogeneous to obtain an adhesive solution; Step 2: Add the silane coupling agent modified biomass substrate and the silane coupling agent modified flame retardant into a high-speed mixer according to the specified ratio. During the mixing process, spray the prepared adhesive solution evenly through a spray gun and continue mixing until the mixture is uniform to obtain the adhesive mixture. Step 3: Lay the adhesive mixture into the mold, place it in a hot press and pre-press it at 60℃ for 1-2 minutes to evaporate the solvent, then raise the temperature to 150-170℃, press it to 3-5 MPa, and hold it at that temperature for 5-15 minutes to allow the thermal initiator to decompose completely and initiate deep curing of the resin; after depressurizing, cool the board to room temperature and demold it to obtain formaldehyde-free, flame-retardant, bio-based board.

7. The preparation method according to claim 6, characterized in that: The low-boiling-point organic solvent is selected from one or more of ethanol, ethyl acetate, acetone, tetrahydrofuran, cyclopentyl methyl ether, isopropanol, dichloromethane, and chloroform.

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