Preparation method of high-performance moisture-proof and flame-retardant impregnated paper

Abstract

This invention relates to the field of impregnated paper, specifically to a method for preparing high-performance moisture-proof and flame-retardant impregnated paper. The invention involves coating both sides of the impregnated paper with adhesive to obtain a moisture-proof and flame-retardant layer. This layer possesses both moisture-proof and flame-retardant functions. It uses melamine-formaldehyde resin as the adhesive matrix, which exhibits superior thermal stability and flammability compared to other adhesive matrices. Specifically, by reacting melamine with formaldehyde and then adding aluminum hydroxide emulsion, the melamine-formaldehyde resin first coats the aluminum hydroxide before the main reaction. This reduces the polarity difference between the inorganic filler flame retardant and the polymer adhesive matrix surface, further improving the compatibility between the polymer adhesive matrix and aluminum hydroxide, preventing agglomeration, and allowing the flame-retardant properties of the inorganic flame retardant to be effectively utilized. The biochar powder used in this invention, due to its porous structure, not only absorbs moisture but also serves as a carrier for the volatile organic flame retardant toluene diphenyl phosphate, enhancing its flame-retardant performance. In summary, this invention requires only one coating to obtain impregnated paper with good mechanical properties and moisture resistance and flame retardancy.

Description

Technical Field

[0001] This invention relates to the field of impregnated paper, and more specifically to a method for preparing high-performance moisture-proof and flame-retardant impregnated paper. Background Technology

[0002] Impregnated paper can form a water-resistant, heat-resistant, wear-resistant, stain-resistant, and glossy resin protective film, which can be made into decorative panels with excellent surface properties and beautiful patterns. Therefore, impregnated paper has been widely used in decoration materials, mainly in furniture, flooring, doors, cabinets, etc.

[0003] Impregnated paper is made primarily from specially produced base paper, impregnated with synthetic resin, dried, and then applied to a particleboard substrate and bonded together under heat to form a decorative facing paper. Currently, the most commonly used synthetic resins for impregnation are phenolic resin, urea-formaldehyde resin, and melamine resin. With societal progress and improved living standards, impregnated paper has become widely used in cabinets, wardrobes, and composite flooring veneers. The safety of impregnated paper, such as its moisture resistance and flame retardancy, is increasingly attracting attention. However, in existing technologies, the moisture resistance and flame retardancy of impregnated paper are relatively poor, and the mechanical properties are significantly reduced with the addition of moisture-resistant and flame-retardant additives, which limits its application. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a moisture-proof and flame-retardant impregnated paper with good mechanical properties, which is both moisture-proof and flame-retardant, in order to solve the technical problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0006] A method for preparing high-performance moisture-proof and flame-retardant impregnated paper includes step (1) impregnating the paper with glue to obtain impregnated paper and step (2) coating both sides of the impregnated paper with glue to obtain a moisture-proof and flame-retardant layer. The technical content of step (1) impregnating the paper with glue can be prepared using the patented technology prior to this invention, or by the technical means commonly used in this field. There are no special restrictions here.

[0007] The specific steps for applying the adhesive in step (2) are as follows:

[0008] (2.1) Preparation of coating adhesive:

[0009] A. Mix 18-25 parts by weight of formaldehyde aqueous solution, 3-7 parts by weight of water, and 6-10 parts by weight of diethylene glycol ether. While stirring continuously, add triethanolamine to adjust the pH to 8.0-8.5, raise the temperature to 72-80℃, and keep the reaction at this temperature for 20-30 minutes.

[0010] B. Add 5-10 parts by weight of melamine and 1-3 parts by weight of polyethylene glycol to the mixed solution in step A, keep warm and stir for 30-40 minutes, then add 5-10 parts by weight of Al(OH)3 emulsion, keep warm and stir for 30-60 minutes.

[0011] C. Continue to add 30-40 parts by weight of melamine, 2-4 parts by weight of caprolactam, and 5-10 parts by weight of biochar powder. Keep warm and stir for 100-120 minutes. Cool to room temperature to obtain the coating adhesive, i.e., the moisture-proof and flame-retardant layer. Apply the coating adhesive to both sides of the impregnated paper obtained in step (1) and dry.

[0012] The Al(OH)3 emulsion is prepared by adding an aqueous solution of emulsifier OP-10 with a mass percentage concentration of 5% to an aqueous suspension of aluminum hydroxide with a mass percentage concentration of 10%, heating to 80℃ and holding for 30-60 minutes to obtain an aluminum hydroxide emulsion.

[0013] The mass ratio of the emulsifier OP-10 to aluminum hydroxide is 0.2:10.

[0014] The biomass char powder is prepared by the following method: 100-200g of biomass char is soaked in 500ml of methyl methacrylate (MTBF) for 30-60min, then 20-50g of N-(2-aminoethyl)-3-aminopropyltriethoxysilane is added and ultrasonically vibrated for 60-120min. After separation, the mixture is dried at 20-40℃. The dried biomass char is then mixed with expanded graphite at a weight ratio of (10-15):1 and ultrasonically vibrated for 30-60min to obtain biomass char powder. Due to its porous structure, the biomass char in the biomass char powder can not only absorb moisture but also serve as a carrier for the volatile organic flame retardant MTBF. The addition of γ-aminopropyltriethoxysilane increases the compatibility of the modified biomass char powder, expanded graphene, and polymer adhesive matrix. Both MTBF and expanded graphene have flame-retardant properties.

[0015] The biochar has a particle size of 60-90 mesh, and the expanded graphite has a particle size of 210-250 mesh.

[0016] Because of the small particle size of expanded graphite, a small portion can still enter the pores of biochar, while the remaining portion enters the adhesive matrix to play its role.

[0017] When exposed to fire, the expanded graphite and aluminum hydroxide in the adhesive matrix are the first to take effect. As time goes on and the temperature rises further, toluene diphenyl phosphate enters the pores of the biochar and begins to play a role. Moreover, when some of the expanded graphite that has entered the biochar pores expands, it causes the biochar pores to partially rupture, further releasing toluene diphenyl phosphate, which further enhances the flame retardant effect.

[0018] The biochar is obtained by pyrolyzing bamboo under nitrogen protection conditions, using a pyrolysis process at a pyrolysis temperature of 1400℃, a heating rate of 270℃ / h, and a pyrolysis time of 3h.

[0019] The formaldehyde aqueous solution is a formaldehyde aqueous solution with a mass fraction of 37%.

[0020] In step (2), the amount of adhesive applied is 20-30 g / m², and the drying temperature is 125-135℃.

[0021] The beneficial effects of this invention are as follows: This invention obtains a moisture-proof and flame-retardant layer by coating adhesive on both sides of impregnated paper. This moisture-proof and flame-retardant layer has both moisture-proof and flame-retardant functions. Specifically, this invention uses melamine-formaldehyde resin as the adhesive matrix, which has better thermal stability and flammability than other adhesive matrices. In particular, by reacting melamine with formaldehyde and then adding aluminum hydroxide emulsion, the melamine-formaldehyde resin first coats aluminum hydroxide before the main reaction, which can reduce the polarity difference between the inorganic filler flame retardant and the polymer adhesive matrix surface, thereby further improving the compatibility between the polymer adhesive matrix and aluminum hydroxide, preventing agglomeration, improving mechanical properties, and allowing the flame-retardant properties of the inorganic flame retardant to be effectively exerted. The biochar in the biochar powder used in this invention, due to its porous structure, can not only absorb moisture but also serve as a carrier for the volatile organic flame retardant toluene diphenyl phosphate, improving flame-retardant performance. In summary, this invention requires only one coating to obtain impregnated paper with good mechanical properties and moisture resistance and flame retardancy. Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Example 1

[0023] A method for preparing high-performance moisture-proof and flame-retardant impregnated paper includes step (1) impregnating the paper with glue to obtain impregnated paper and step (2) coating both sides of the impregnated paper with glue to obtain a moisture-proof and flame-retardant layer.

[0024] The specific steps for applying the adhesive in step (2) are as follows:

[0025] (2.1) Preparation of coating adhesive:

[0026] A. Mix 18 parts by weight of formaldehyde aqueous solution, 3 parts by weight of water, and 6 parts by weight of diethylene glycol ether. Add triethanolamine while stirring continuously to adjust the pH to 8.0, raise the temperature to 72°C, and keep the reaction at this temperature for 20 minutes.

[0027] B. Add 5 parts by weight of melamine and 1 part by weight of polyethylene glycol to the mixed solution in step A, keep warm and stir for 30 minutes, then add 5 parts by weight of Al(OH)3 emulsion, keep warm and stir for 60 minutes.

[0028] C. Continue to add 30 parts by weight of melamine, 2 parts by weight of caprolactam, and 5 parts by weight of biomass charcoal powder. Keep warm and stir for 100 minutes. Cool to room temperature to obtain the coating adhesive, i.e. the moisture-proof and flame-retardant layer. Apply the coating adhesive to both sides of the impregnated paper obtained in step (1) and dry.

[0029] The Al(OH)3 emulsion is prepared by adding an aqueous solution of emulsifier OP-10 with a mass percentage concentration of 5% to an aqueous suspension of aluminum hydroxide with a mass percentage concentration of 10%, heating to 80°C and holding for 30 minutes to obtain an aluminum hydroxide emulsion.

[0030] The mass ratio of the emulsifier OP-10 to aluminum hydroxide is 0.2:10.

[0031] The biochar powder is prepared by the following method: 100g of biochar is soaked in 500ml of toluene diphenyl phosphate for 30min, then 20g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is added and ultrasonically vibrated for 60min, separated, dried at 20℃, and then the dried biochar is mixed with expanded graphite at a weight ratio of 10-15:1 and ultrasonically vibrated for 30min to obtain biochar powder.

[0032] The biochar has a particle size of 60 mesh, and the expanded graphite has a particle size of 210 mesh.

[0033] The biochar is obtained by pyrolyzing bamboo under nitrogen protection conditions, using a pyrolysis process at a pyrolysis temperature of 1400℃, a heating rate of 270℃ / h, and a pyrolysis time of 3h.

[0034] The formaldehyde aqueous solution is a formaldehyde aqueous solution with a mass fraction of 37%.

[0035] In step (2), the amount of adhesive applied is 20g / ㎡, and the drying temperature is 125℃. Example 2

[0036] A method for preparing high-performance moisture-proof and flame-retardant impregnated paper includes step (1) impregnation with glue to obtain impregnated paper and step (2) coating with glue to obtain a moisture-proof and flame-retardant layer. The specific steps of step (2) glue coating are as follows:

[0037] (2.1) Preparation of coating adhesive:

[0038] A. Mix 22 parts by weight of formaldehyde aqueous solution, 4 parts by weight of water, and 7 parts by weight of diethylene glycol ether. Add triethanolamine while stirring continuously to adjust the pH to 8.2, raise the temperature to 78°C, and keep the reaction at this temperature for 25 minutes.

[0039] B. Add 8 parts by weight of melamine and 2 parts by weight of polyethylene glycol to the mixed solution in step A, keep warm and stir for 35 minutes, then add 8 parts by weight of Al(OH)3 emulsion, keep warm and stir for 50 minutes.

[0040] C. Continue to add 35 parts by weight of melamine, 3 parts by weight of caprolactam, and 8 parts by weight of biochar powder. Keep warm and stir for 110 minutes. Cool to room temperature to obtain the coating adhesive, i.e. the moisture-proof and flame-retardant layer. Apply the coating adhesive to both sides of the impregnated paper obtained in step (1) and dry.

[0041] The Al(OH)3 emulsion is prepared by adding an aqueous solution of emulsifier OP-10 with a mass percentage concentration of 5% to an aqueous suspension of aluminum hydroxide with a mass percentage concentration of 10%, heating to 80℃ and holding for 45 minutes to obtain an aluminum hydroxide emulsion.

[0042] The mass ratio of the emulsifier OP-10 to aluminum hydroxide is 0.2:10.

[0043] The biochar powder is prepared by the following method: 150g of biochar is soaked in 500ml of toluene diphenyl phosphate for 50min, then 30g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is added and ultrasonically vibrated for 90min, separated, dried at 30℃, and then the dried biochar is mixed with expanded graphite at a weight ratio of 12:1 and ultrasonically vibrated for 40min to obtain biochar powder.

[0044] The biochar has a particle size of 80 mesh, and the expanded graphite has a particle size of 220 mesh.

[0045] The biochar is obtained by pyrolyzing bamboo under nitrogen protection conditions, using a pyrolysis process at a pyrolysis temperature of 1400℃, a heating rate of 270℃ / h, and a pyrolysis time of 3h.

[0046] The formaldehyde aqueous solution is a formaldehyde aqueous solution with a mass fraction of 37%.

[0047] In step (2), the amount of adhesive applied is 25g / ㎡, and the drying temperature is 130℃. Example 3

[0048] A method for preparing high-performance moisture-proof and flame-retardant impregnated paper includes step (1) impregnation with glue to obtain impregnated paper and step (2) coating with glue to obtain a moisture-proof and flame-retardant layer. The specific steps of step (2) glue coating are as follows:

[0049] (2.1) Preparation of coating adhesive:

[0050] A. Mix 25 parts by weight of formaldehyde aqueous solution, 7 parts by weight of water, and 10 parts by weight of diethylene glycol ether. Add triethanolamine while stirring continuously to adjust the pH to 8.5, raise the temperature to 80°C, and keep the reaction at this temperature for 30 minutes.

[0051] B. Add 10 parts by weight of melamine and 3 parts by weight of polyethylene glycol to the mixed solution in step A, keep warm and stir for 40 minutes, then add 10 parts by weight of Al(OH)3 emulsion, keep warm and stir for 60 minutes.

[0052] C. Continue to add 40 parts by weight of melamine, 4 parts by weight of caprolactam, and 10 parts by weight of biochar powder. Keep warm and stir for 120 minutes. Cool to room temperature to obtain the coating adhesive, i.e. the moisture-proof and flame-retardant layer. Apply the coating adhesive to both sides of the impregnated paper obtained in step (1) and dry.

[0053] The Al(OH)3 emulsion is prepared by adding an aqueous solution of emulsifier OP-10 with a mass percentage concentration of 5% to an aqueous suspension of aluminum hydroxide with a mass percentage concentration of 10%, heating to 80°C and holding for 60 minutes to obtain an aluminum hydroxide emulsion.

[0054] The mass ratio of the emulsifier OP-10 to aluminum hydroxide is 0.2:10.

[0055] The biochar powder is prepared by the following method: 200g of biochar is soaked in 500ml of toluene diphenyl phosphate for 60min, then 50g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is added and ultrasonically vibrated for 120min, separated, dried at 40℃, and then the dried biochar is mixed with expanded graphite at a weight ratio of 15:1 and ultrasonically vibrated for 60min to obtain biochar powder.

[0056] The biochar has a particle size of 90 mesh, and the expanded graphite has a particle size of 250 mesh.

[0057] The biochar is obtained by pyrolyzing bamboo under nitrogen protection conditions, using a pyrolysis process at a pyrolysis temperature of 1400℃, a heating rate of 270℃ / h, and a pyrolysis time of 3h.

[0058] The formaldehyde aqueous solution is a formaldehyde aqueous solution with a mass fraction of 37%.

[0059] In step (2), the amount of adhesive applied is 30g / ㎡, and the drying temperature is 135℃.

[0060] Comparative Example 1

[0061] The difference between this embodiment and Embodiment 2 is that in this embodiment, melamine is added all at once. Specifically,

[0062] A method for preparing high-performance moisture-proof and flame-retardant impregnated paper includes step (1) impregnation with glue to obtain impregnated paper and step (2) coating with glue to obtain a moisture-proof and flame-retardant layer. The specific steps of step (2) glue coating are as follows:

[0063] (2.1) Preparation of coating adhesive:

[0064] A. Mix 22 parts by weight of formaldehyde aqueous solution, 4 parts by weight of water, and 7 parts by weight of diethylene glycol ether. Add triethanolamine while stirring continuously to adjust the pH to 8.2, raise the temperature to 78°C, and keep the reaction at this temperature for 25 minutes.

[0065] B. Add 43 parts by weight of melamine, 2 parts by weight of polyethylene glycol, 3 parts by weight of caprolactam, 8 parts by weight of Al(OH)3 emulsion, and 8 parts by weight of biomass charcoal powder to the mixed solution in step A, keep warm and stir for 110 minutes, cool to room temperature to obtain the coating adhesive, i.e. the moisture-proof and flame-retardant layer, apply the coating adhesive to both sides of the impregnated paper obtained in step (1), and dry.

[0066] The Al(OH)3 emulsion is prepared by adding an aqueous solution of emulsifier OP-10 with a mass percentage concentration of 5% to an aqueous suspension of aluminum hydroxide with a mass percentage concentration of 10%, heating to 80℃ and holding for 45 minutes to obtain an aluminum hydroxide emulsion.

[0067] The mass ratio of the emulsifier OP-10 to aluminum hydroxide is 0.2:10.

[0068] The biochar powder is prepared by the following method: 150g of biochar is soaked in 500ml of toluene diphenyl phosphate for 50min, then 30g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is added and ultrasonically vibrated for 90min, separated, dried at 30℃, and then the dried biochar is mixed with expanded graphite at a weight ratio of 12:1 and ultrasonically vibrated for 40min to obtain biochar powder.

[0069] The biochar has a particle size of 80 mesh, and the expanded graphite has a particle size of 220 mesh.

[0070] The biochar is obtained by pyrolyzing bamboo under nitrogen protection conditions, using a pyrolysis process at a pyrolysis temperature of 1400℃, a heating rate of 270℃ / h, and a pyrolysis time of 3h.

[0071] The formaldehyde aqueous solution is a formaldehyde aqueous solution with a mass fraction of 37%.

[0072] In step (2), the amount of adhesive applied is 25g / ㎡, and the drying temperature is 130℃.

[0073] Comparative Example 2

[0074] The difference between this embodiment and Embodiment 2 is that the biochar powder used in this invention is ordinary untreated biochar powder.

[0075] A method for preparing high-performance moisture-proof and flame-retardant impregnated paper includes step (1) impregnation with glue to obtain impregnated paper and step (2) coating with glue to obtain a moisture-proof and flame-retardant layer. The specific steps of step (2) glue coating are as follows:

[0076] (2.1) Preparation of coating adhesive:

[0077] A. Mix 22 parts by weight of formaldehyde aqueous solution, 4 parts by weight of water, and 7 parts by weight of diethylene glycol ether. Add triethanolamine while stirring continuously to adjust the pH to 8.2, raise the temperature to 78°C, and keep the reaction at this temperature for 25 minutes.

[0078] B. Add 8 parts by weight of melamine and 2 parts by weight of polyethylene glycol to the mixed solution in step A, keep warm and stir for 35 minutes, then add 8 parts by weight of Al(OH)3 emulsion, keep warm and stir for 50 minutes.

[0079] C. Continue to add 35 parts by weight of melamine, 3 parts by weight of caprolactam, and 8 parts by weight of biochar powder. Keep warm and stir for 110 minutes. Cool to room temperature to obtain the coating adhesive, i.e. the moisture-proof and flame-retardant layer. Apply the coating adhesive to both sides of the impregnated paper obtained in step (1) and dry.

[0080] The Al(OH)3 emulsion is prepared by adding an aqueous solution of emulsifier OP-10 with a mass percentage concentration of 5% to an aqueous suspension of aluminum hydroxide with a mass percentage concentration of 10%, heating to 80℃ and holding for 45 minutes to obtain an aluminum hydroxide emulsion.

[0081] The mass ratio of the emulsifier OP-10 to aluminum hydroxide is 0.2:10.

[0082] The biochar powder is obtained by pyrolyzing bamboo under nitrogen protection conditions, with a pyrolysis temperature of 1400℃, a heating rate of 270℃ / h, and a pyrolysis time of 3h.

[0083] The formaldehyde aqueous solution is a formaldehyde aqueous solution with a mass fraction of 37%.

[0084] In step (2), the amount of adhesive applied is 25g / ㎡, and the drying temperature is 130℃.

[0085] The impregnated papers of Examples 1-3 and Comparative Examples 1-2 were subjected to formation tests, as shown in the table below. The test standards were as follows: tensile strength: GB / T13022-1991, impact strength: GB / T1843-2008, limiting oxygen index was tested according to GB / T 2406.2-2009, and moisture regain test: the method was to place the impregnated paper at a high humidity of 40℃ and 95% for 24 hours to allow it to regain moisture. The moisture content of the impregnated paper was measured by a DM200P non-destructive inductive paper moisture meter, which can achieve a simple contact instantaneous reading to obtain the moisture regain of the paper.

[0086] As can be seen from the table above, in Comparative Example 1, melamine was added all at once, without reacting with formaldehyde first, followed by the addition of aluminum hydroxide emulsion, and then the remaining melamine for the main reaction. The possible reason for this is that it caused agglomeration of aluminum hydroxide, affecting the product's mechanical and flame-retardant properties, but not its hygroscopicity. In Comparative Example 2, the biomass charcoal powder used in this invention was ordinary untreated biomass powder. While its hygroscopicity was not reduced, its flame-retardant properties were significantly reduced. This is due to the absence of toluene diphenyl phosphate and expanded graphite, which play a crucial role in flame retardancy. The mechanical properties also decreased because N-(2-aminoethyl)-3-aminopropyltrimethoxysilane did not participate in the modification of the biomass charcoal, leading to reduced compatibility and consequently, lower mechanical properties.

[0087] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0088] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A process for the preparation of high performance moisture resistant flame retardant impregnated paper characterized by: It includes step (1) impregnating the paper with glue to obtain impregnated paper and step (2) coating both sides of the impregnated paper with glue to obtain a moisture-proof and flame-retardant layer. The specific steps for applying the adhesive in step (2) are as follows: (2.1) Preparation of coating adhesive: A. Mix 18 parts by weight of formaldehyde aqueous solution, 3 parts by weight of water, and 6 parts by weight of diethylene glycol ether. Add triethanolamine while stirring continuously to adjust the pH to 8.0, raise the temperature to 72°C, and keep the reaction at this temperature for 20 minutes. B. Add 5 parts by weight of melamine and 1 part by weight of polyethylene glycol to the mixed solution in step A, keep warm and stir for 30 minutes, then add 5 parts by weight of Al(OH)3 emulsion, keep warm and stir for 60 minutes. C. Continue to add 30 parts by weight of melamine, 2 parts by weight of caprolactam, and 5 parts by weight of biochar powder. Keep warm and stir for 100 minutes. Cool to room temperature to obtain the coating adhesive, i.e., the moisture-proof and flame-retardant layer. Apply the coating adhesive to both sides of the impregnated paper obtained in step (1) and dry. The Al(OH)3 emulsion is prepared by adding a 5% (w / w) aqueous solution of emulsifier OP-10 to a 10% (w / w) aqueous suspension of aluminum hydroxide, heating to 80°C and holding for 30 minutes to obtain the aluminum hydroxide emulsion. The mass ratio of the emulsifier OP-10 to aluminum hydroxide is 0.2:

10. The biochar powder is prepared by the following method: 100g of biochar is soaked in 500ml of toluene diphenyl phosphate for 30min, then 20g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is added and ultrasonically vibrated for 60min, separated, and dried at 20℃. The dried biochar is then mixed with expanded graphite at a weight ratio of 10-15:1 and ultrasonically vibrated for 30min to obtain biochar powder. The biochar has a particle size of 60 mesh, and the expanded graphite has a particle size of 210 mesh. The biochar is obtained by pyrolyzing bamboo under nitrogen protection conditions, using a pyrolysis process at a temperature of 1400℃, a heating rate of 270℃ / h, and a pyrolysis time of 3h. The formaldehyde aqueous solution is a formaldehyde aqueous solution with a mass fraction of 37%. In step (2), the amount of adhesive applied is 20g / ㎡, and the drying temperature is 125℃.

2. A process for the preparation of high performance moisture resistant flame retardant impregnated paper characterized by: It includes step (1) impregnation with glue to obtain impregnated paper and step (2) coating with glue to obtain a moisture-proof and flame-retardant layer. The specific steps of step (2) coating with glue are as follows: (2.1) Preparation of coating adhesive: A. Mix 22 parts by weight of formaldehyde aqueous solution, 4 parts by weight of water, and 7 parts by weight of diethylene glycol ether. Add triethanolamine while stirring continuously to adjust the pH to 8.2, raise the temperature to 78°C, and keep the reaction at this temperature for 25 minutes. B. Add 8 parts by weight of melamine and 2 parts by weight of polyethylene glycol to the mixed solution in step A, keep warm and stir for 35 minutes, then add 8 parts by weight of Al(OH)3 emulsion, keep warm and stir for 50 minutes. C. Continue to add 35 parts by weight of melamine, 3 parts by weight of caprolactam, and 8 parts by weight of biochar powder. Keep warm and stir for 110 minutes. Cool to room temperature to obtain the coating adhesive, i.e., the moisture-proof and flame-retardant layer. Apply the coating adhesive to both sides of the impregnated paper obtained in step (1) and dry. The Al(OH)3 emulsion is prepared by adding a 5% (w / w) aqueous solution of emulsifier OP-10 to a 10% (w / w) aqueous suspension of aluminum hydroxide, heating to 80°C and holding for 45 minutes to obtain the aluminum hydroxide emulsion. The mass ratio of the emulsifier OP-10 to aluminum hydroxide is 0.2:

10. The biochar powder was prepared by the following method: 150g of biochar was soaked in 500ml of toluene diphenyl phosphate for 50min, then 30g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was added and ultrasonically vibrated for 90min. After separation, the mixture was dried at 30℃. The dried biochar was then mixed with expanded graphite at a weight ratio of 12:1 and ultrasonically vibrated for 40min to obtain biochar powder. The biochar has a particle size of 80 mesh, and the expanded graphite has a particle size of 220 mesh. The biochar is obtained by pyrolyzing bamboo under nitrogen protection conditions, using a pyrolysis process at a temperature of 1400℃, a heating rate of 270℃ / h, and a pyrolysis time of 3h. The formaldehyde aqueous solution is a formaldehyde aqueous solution with a mass fraction of 37%. In step (2), the amount of adhesive applied is 25g / ㎡, and the drying temperature is 130℃.

3. A method for preparing high-performance moisture-proof and flame-retardant impregnated paper, characterized in that: It includes step (1) impregnation with glue to obtain impregnated paper and step (2) coating with glue to obtain a moisture-proof and flame-retardant layer. The specific steps of step (2) coating with glue are as follows: (2.1) Preparation of coating adhesive: A. Mix 25 parts by weight of formaldehyde aqueous solution, 7 parts by weight of water, and 10 parts by weight of diethylene glycol ether. Add triethanolamine while stirring continuously to adjust the pH to 8.5, raise the temperature to 80°C, and keep the reaction at this temperature for 30 minutes. B. Add 10 parts by weight of melamine and 3 parts by weight of polyethylene glycol to the mixed solution in step A, keep warm and stir for 40 minutes, then add 10 parts by weight of Al(OH)3 emulsion, keep warm and stir for 60 minutes. C. Continue to add 40 parts by weight of melamine, 4 parts by weight of caprolactam, and 10 parts by weight of biochar powder. Keep warm and stir for 120 minutes. Cool to room temperature to obtain the coating adhesive, i.e., the moisture-proof and flame-retardant layer. Apply the coating adhesive to both sides of the impregnated paper obtained in step (1) and dry. The Al(OH)3 emulsion is prepared by adding a 5% (w / w) aqueous solution of emulsifier OP-10 to a 10% (w / w) aqueous suspension of aluminum hydroxide, heating to 80°C and holding for 60 minutes to obtain the aluminum hydroxide emulsion. The mass ratio of the emulsifier OP-10 to aluminum hydroxide is 0.2:

10. The biochar powder was prepared by the following method: 200g of biochar was soaked in 500ml of toluene diphenyl phosphate for 60min, then 50g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was added and ultrasonically vibrated for 120min. After separation, the mixture was dried at 40℃. The dried biochar was then mixed with expanded graphite at a weight ratio of 15:1 and ultrasonically vibrated for 60min to obtain biochar powder. The biochar has a particle size of 90 mesh, and the expanded graphite has a particle size of 250 mesh. The biochar is obtained by pyrolyzing bamboo under nitrogen protection conditions, using a pyrolysis process at a temperature of 1400℃, a heating rate of 270℃ / h, and a pyrolysis time of 3h. The formaldehyde aqueous solution is a formaldehyde aqueous solution with a mass fraction of 37%. In step (2), the amount of adhesive applied is 30g / ㎡, and the drying temperature is 135℃.

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