Fireproof flame-retardant sealant as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of sealants, and particularly relates to a fireproof flame-retardant sealant as well as a preparation method and application thereof. The fireproof flame-retardant sealant provided by the invention comprises the following components in parts by weight: 100 parts of alpha, omega-dihydroxy polydimethylsiloxane; 60 to 80 parts of trimethyl polydimethylsiloxane; 10-20 parts of an aluminum phosphate coated boron nitride composite material; 5 to 15 parts of aluminum diethylphosphinate; 3-7 parts of tannic acid modified black phosphorus; 0.5-1 part of a catalyst; 10 to 20 parts of a cross-linking agent; and 4-8 parts of a silane coupling agent. The aluminum phosphate coated boron nitride composite material, the aluminum diethylphosphinate and the tannic acid modified black phosphorus are added into the raw materials of the sealant, and the synergistic interaction performance among the components is utilized, so that the flame-retardant and fireproof performance of the sealant is remarkably improved, and the sealant has a very good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of sealant technology. More specifically, it relates to a fire-retardant sealant, its preparation method, and its application. Background Technology

[0002] Silicone sealant, as a novel type of organosilicon elastomer, can cross-link and cure at room temperature. Its operating temperature range is -50 to 180°C. Due to its excellent adhesion to various substrates, ability to prevent dust and moisture from penetrating the interior of products, and superior electrical insulation, chemical stability, aging resistance, and physiological inertness, silicone sealant is widely used. However, silicone sealant itself is flammable and will burn when exposed to an open flame; therefore, researching the flame-retardant properties of sealants has become an important development trend.

[0003] When flame-retardant silicone sealant is exposed to high temperatures or flames, the flame retardants within the material will take effect, preventing the spread of fire and ensuring the sealing and safety of the building in the event of a fire, thus buying valuable time for the evacuation of people.

[0004] CN120665545A discloses a ceramicized fire-resistant sealant for bridges, a fireproof structure, preparation equipment, and preparation method, relating to the field of sealant technology for bridges. The specific components and contents of the ceramicized fire-resistant sealant for bridges are as follows: 100 parts MS polymer; 0-100 parts plasticizer; 80-150 parts aluminum hydroxide; 80-150 parts modified wollastonite; 50-100 parts calcium carbonate; 10-20 parts zinc borate; 10-20 parts melamine polyphosphate; 5-10 parts dipentaerythritol; 5-10 parts dehydrating agent; 5-10 parts adhesion promoter; and 0.5-2 parts catalyst. The bridge uses ceramic fire-resistant sealant. After vulcanization, the rubber body formed transforms into a self-supporting ceramic body under high temperature or open flame conditions, preventing the flame from spreading into the material and thus achieving the purpose of flame retardancy and fire prevention. At the same time, the mechanical properties do not significantly decrease before and after thermal aging, and it still maintains good elasticity. Furthermore, the paint has excellent adhesion to it after vulcanization, ensuring its performance.

[0005] CN120648436A discloses a silicone sealant composed of the following raw materials in parts by weight: 15-30 parts of hydroxyl-terminated polysiloxane, 10-15 parts of PET polyester, 5-10 parts of sodium isophthalate-5-sulfonate, 2-5 parts of 3-sulfonate-butanetetrol, 5-8 parts of crosslinking agent, 25-50 parts of flame retardant, 10-30 parts of filler, 0.5-2 parts of chain extender, 0.5-2 parts of tackifier, and 0.5-1 part of catalyst. The 3-sulfonate-butanetetrol introduces -SOH sulfonate groups, which, after combining with PET polyester, generate hydrophobic groups, thereby preventing moisture from entering through the tiny pores on the product surface, resulting in better waterproof performance. The silicone components of the flame retardant crosslink with each other, forming a Si-O-Si network structure inside the sealant. The decomposition products help prevent further combustion, thus achieving a flame-retardant effect. Grafting with silicon groups can greatly reduce the formation of tiny voids in the internal structure, thus ensuring that the sealant has good waterproof properties.

[0006] CN116589969A discloses a low-hardness, lightweight, flame-retardant sealant, its preparation method, and its application. This sealant is mainly prepared by mixing the following raw materials: a 20,000 viscosity hydroxyl-terminated polydimethylsiloxane polymer, a high viscosity hydroxyl-terminated polydimethylsiloxane polymer (viscosity at 25℃ is 450,000-550,000 cps), a plasticizer, a flame-retardant filler, a lightweighting agent, a thixotropic agent, a crosslinking agent, a curing agent, and an organotitanium catalyst; wherein the plasticizer is prepared by mixing the following raw materials: dimethyldimethoxysilane, methylphenyldimethoxysilane, trifluoropropylmethyldimethoxysilane, hexamethyldisiloxane, anhydrous methanol, concentrated hydrochloric acid, and deionized water. The prepared sealant has a Shore A hardness of 8 or less, resistance to high and low temperatures, aging resistance, and good flexibility, and can be applied in the field of power batteries.

[0007] CN120082322A discloses a silicone fire-retardant sealant for building applications. This invention incorporates quaternary ammonium salt-modified silicone oil during the preparation of the silicone sealant base. Quaternary ammonium salt groups are introduced through a ring-opening reaction between terminal epoxy polyether and trimethylamine hydrochloride, thereby disrupting the cell membrane structure of microorganisms and achieving broad-spectrum antibacterial activity. Furthermore, the chemical bonding between the quaternary ammonium salt groups and the silicone oil backbone avoids the migration and failure problems of traditional antifungal agents. Secondly, the modified aluminum hydroxide in this invention improves the flame-retardant properties of the sealant. After modification with vinyltrimethoxysilane, aluminum hydroxide enhances its surface hydrophobicity and improves its dispersibility in the base sealant. It also exhibits high heat absorption efficiency during thermal decomposition, which slows down the combustion rate and improves fire resistance. The synergistic effect of modified aluminum hydroxide combined with melamine and modified hollow glass microspheres enables the prepared silicone fire-retardant sealant to possess excellent fire-retardant properties.

[0008] Adding flame-retardant components to silicone sealants can improve their flame-retardant and fire-resistant properties. However, existing flame-retardant components are complex or have poor flame-retardant effects, which cannot meet current needs. Summary of the Invention

[0009] The technical problem this invention aims to solve is to overcome the defects and shortcomings of existing technologies and provide a fire-retardant sealant, its preparation method, and its application. This invention significantly improves the flame-retardant and fire-resistant properties of the sealant by adding aluminum phosphate-coated boron nitride composite material, aluminum diethylphosphinate, and tannic acid-modified black phosphorus to the sealant raw materials, utilizing the synergistic effects of the components. This results in a sealant with excellent application prospects.

[0010] The purpose of this invention is to provide a fire-retardant sealant.

[0011] Another objective of this invention is to provide a method for preparing a fire-retardant sealant.

[0012] Another objective of this invention is to provide an application of a fire-retardant sealant in the construction field.

[0013] The above-mentioned objective of this invention is achieved through the following technical solution:

[0014] 1. A fire-retardant sealant, comprising the following components by weight:

[0015] 100 parts of α,ω-dihydroxypolydimethylsiloxane;

[0016] 60-80 parts of trimethylpolydimethylsiloxane;

[0017] 10-20 parts of aluminum phosphate-coated boron nitride composite material;

[0018] 5-15 parts of aluminum diethylphosphinate;

[0019] 3-7 parts of tannic acid-modified black phosphorus;

[0020] Catalyst 0.5~1 part;

[0021] 10-20 parts of crosslinking agent;

[0022] 4-8 parts of silane coupling agent.

[0023] Furthermore, in this invention, a preferred embodiment of the method for preparing the aluminum phosphate-coated boron nitride composite material includes the following steps:

[0024] Boron nitride nanosheets were ultrasonically dispersed in deionized water to obtain a boron nitride nanosheet dispersion. Hydrochloric acid solution was added dropwise to adjust the pH of the dispersion to 2-3, resulting in dispersion A. Aluminum hydroxide and phosphoric acid were added to deionized water and stirred to obtain solution B. Solution B was then slowly added dropwise to dispersion A while stirring vigorously. Subsequently, ammonia solution was added dropwise to adjust the pH of the solution to 5-7. The solution was then centrifuged, washed, and vacuum dried to constant weight to obtain aluminum phosphate-coated boron nitride composite material.

[0025] Preferably, the concentration of the hydrochloric acid is 25-35 wt%; the mass ratio of the boron nitride nanosheets, aluminum hydroxide, and phosphoric acid is 10:0.5-0.7:4-5.

[0026] Preferably, the stirring time is 30-50 min; the concentration of the ammonia water is 25 wt%; the vigorous stirring time is 25-35 min; and the vacuum drying temperature is 60-80℃.

[0027] Furthermore, in this invention, a further preferred technical solution is provided, wherein the preparation method of tannic acid-modified black phosphorus includes the following steps:

[0028] (1) Amorphous red phosphorus and nitrogen-containing compounds are added to a solvent and then subjected to a solvothermal reaction. After the reaction is completed, the product is obtained. Finally, the product is filtered, washed and dried to prepare the nitrogen-doped black phosphorus composite material.

[0029] (2) The nitrogen-doped black phosphorus and tannic acid obtained in step (1) are ultrasonically dispersed in water, stirred, centrifuged, washed, and vacuum dried to obtain tannic acid-modified black phosphorus.

[0030] Preferably, in step (1), the mass ratio of the amorphous red phosphorus to the nitrogen-containing compound is 1:5 to 10:1; the nitrogen-containing compound is at least one of urea, thiourea, and melamine; the solvent is at least one of ethylenediamine, propylenediamine, and butanediamine; the solvothermal reaction conditions are a reaction at 150 to 200°C for 5 to 20 hours; and the drying is a drying at 80 to 100°C for 10 to 18 hours.

[0031] Preferably, in step (2), the stirring conditions are stirring at a speed of 500~700 rpm for 1~2 hours; the vacuum drying is vacuum drying at 40~80℃ for 10~14 hours; and the mass ratio of nitrogen-doped black phosphorus to tannic acid is 1:0.8~1.2.

[0032] Furthermore, the α,ω-dihydroxypolydimethylsiloxane has a viscosity of 15000cps to 25000cps; the catalyst is dibutyltin dilaurate or dibutyltin diacetate; the crosslinking agent is methyltributanone oxime silane or propyltributanone oxime silane; and the silane coupling agent is KH550 or KH560.

[0033] The preparation method of the fire-retardant sealant described above includes the following steps:

[0034] (1) The α,ω-dihydroxy polydimethylsiloxane, trimethyl polydimethylsiloxane, aluminum phosphate-coated boron nitride composite material, aluminum diethylphosphonate and tannic acid-modified black phosphorus are added to a planetary machine and dehydrated for 120-200 min at a temperature of 110℃~150℃ and a vacuum degree of -0.06MPa~-0.08MPa to obtain the base material;

[0035] (2) After the base material is cooled to room temperature, the crosslinking agent, silane coupling agent and catalyst are added in sequence, and the mixture is stirred for 60 to 120 minutes under a vacuum of -0.06 MPa to -0.08 MPa to obtain the fireproof and flame-retardant sealant.

[0036] Based on the above-described application of a fire-retardant sealant in the construction field.

[0037] The present invention has the following beneficial effects:

[0038] This invention achieves synergistic effects by coating boron nitride with aluminum phosphate, dispersing the aluminum phosphate onto the surface of boron nitride and obtaining a composite material with superior flame retardant properties. Black phosphorus enhances the flame retardant properties of sealants through its shielding and heat absorption effects. Tannic acid modification promotes the dispersibility of black phosphorus while also improving the flame retardancy and smoke suppression properties of the sealant. The combination of the aluminum phosphate-coated boron nitride composite material and aluminum diethylphosphinate synergistically improves the flame retardant and fire-retardant properties of the sealant. The sealant prepared by this invention exhibits excellent flame retardant and fire-retardant properties, uses readily available materials, and has wide applications. Detailed Implementation

[0039] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0040] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0041] Example 1

[0042] A fire-retardant sealant, comprising the following components by weight:

[0043] 100 parts of α,ω-dihydroxypolydimethylsiloxane;

[0044] 80 parts of trimethylpolydimethylsiloxane;

[0045] 10 parts of aluminum phosphate-coated boron nitride composite material;

[0046] 15 parts of aluminum diethylphosphinate;

[0047] Three parts of tannic acid-modified black phosphorus;

[0048] 1 part catalyst;

[0049] 10 parts crosslinking agent;

[0050] 8 parts of silane coupling agent.

[0051] The preparation method of the aluminum phosphate-coated boron nitride composite material includes the following steps:

[0052] 10g of boron nitride nanosheets were ultrasonically dispersed in 100mL of deionized water to obtain a boron nitride nanosheet dispersion. A 35wt% hydrochloric acid solution was added dropwise to make the pH of the dispersion 2, thus obtaining dispersion A.

[0053] 0.7 g aluminum hydroxide and 5 g phosphoric acid were added to 100 mL of deionized water and stirred for 50 min to obtain solution B. Solution B was then slowly added dropwise to dispersion A and stirred vigorously for 25 min. Subsequently, 25 wt% ammonia solution was added dropwise to adjust the pH of the solution to 7. The solution was centrifuged, washed, and vacuum dried at 80 °C to constant weight to obtain aluminum phosphate coated boron nitride composite material.

[0054] The preparation method of the tannic acid modified black phosphorus includes the following steps:

[0055] (1) Add 10g of amorphous red phosphorus and 1g of urea to 150mL of ethylenediamine, and then react with solvent at 200℃ for 5h. After the reaction is completed, the product is obtained. Finally, the product is filtered, washed and dried at 100℃ for 10h to prepare the nitrogen-doped black phosphorus composite material.

[0056] (2) Disperse 10g of nitrogen-doped black phosphorus and 12g of tannic acid in 150mL of water by ultrasonication, stir at 700rpm for 1h, centrifuge, wash, and vacuum dry at 80℃ for 10h to obtain tannic acid-modified black phosphorus.

[0057] The α,ω-dihydroxypolydimethylsiloxane has a viscosity of 25000 cps;

[0058] The catalyst is dibutyltin dilaurate;

[0059] The crosslinking agent is methyltributanone oxime silane;

[0060] The silane coupling agent is KH550.

[0061] A method for preparing a fire-retardant sealant, the method comprising the following steps:

[0062] (1) The α,ω-dihydroxy polydimethylsiloxane, trimethyl polydimethylsiloxane, aluminum phosphate-coated boron nitride composite material, aluminum diethylphosphonate and tannic acid-modified black phosphorus were added to a planetary machine and dehydrated for 180 min at a temperature of 130℃ and a vacuum of -0.07MPa to obtain the base material.

[0063] (2) After the base material is cooled to room temperature, the crosslinking agent, silane coupling agent and catalyst are added in sequence, and the mixture is stirred for 100 min under a vacuum of -0.078 MPa to obtain the fireproof and flame-retardant sealant.

[0064] Example 2

[0065] A fire-retardant sealant, comprising the following components by weight:

[0066] 100 parts of α,ω-dihydroxypolydimethylsiloxane;

[0067] 60 parts of trimethylpolydimethylsiloxane;

[0068] 20 parts of aluminum phosphate-coated boron nitride composite material;

[0069] 5 parts of aluminum diethylphosphinate;

[0070] Tannic acid-modified black phosphorus, 7 parts;

[0071] 0.5 parts catalyst;

[0072] 20 parts of crosslinking agent;

[0073] 4 parts of silane coupling agent.

[0074] The preparation method of the aluminum phosphate-coated boron nitride composite material includes the following steps:

[0075] 10g of boron nitride nanosheets were ultrasonically dispersed in 100mL of deionized water to obtain a boron nitride nanosheet dispersion. A 25wt% hydrochloric acid solution was added dropwise to make the pH of the dispersion 2, thus obtaining dispersion A.

[0076] 0.5 g of aluminum hydroxide and 4 g of phosphoric acid were added to 100 mL of deionized water and stirred for 30 min to obtain solution B. Solution B was then slowly added dropwise to dispersion A and stirred vigorously for 35 min. Subsequently, 25 wt% ammonia solution was added dropwise to adjust the pH of the solution to 5. The solution was centrifuged, washed, and vacuum dried at 60 °C to constant weight to obtain aluminum phosphate-coated boron nitride composite material.

[0077] The preparation method of the tannic acid modified black phosphorus includes the following steps:

[0078] (1) Add 1g of amorphous red phosphorus and 5g of thiourea to 150mL of propylenediamine, and then react with solvent at 150℃ for 20h. After the reaction is completed, the product is obtained. Finally, the product is filtered, washed and dried at 80℃ for 18h to prepare the nitrogen-doped black phosphorus composite material.

[0079] (2) Disperse 10g of nitrogen-doped black phosphorus and 8g of tannic acid in 150mL of water by ultrasonication, stir at 500rpm for 2h, centrifuge, wash, and vacuum dry at 40℃ for 14h to obtain tannic acid-modified black phosphorus.

[0080] The α,ω-dihydroxypolydimethylsiloxane has a viscosity of 15000 cps;

[0081] The catalyst is dibutyltin diacetate;

[0082] The crosslinking agent is propyltributylone oxime silane;

[0083] The silane coupling agent is KH560.

[0084] A method for preparing a fire-retardant sealant, wherein the preparation method is the same as in Example 1.

[0085] Example 3

[0086] A fire-retardant sealant, comprising the following components by weight:

[0087] 100 parts of α,ω-dihydroxypolydimethylsiloxane;

[0088] 70 parts of trimethylpolydimethylsiloxane;

[0089] 15 parts of aluminum phosphate-coated boron nitride composite material;

[0090] 10 parts of aluminum diethylphosphinate;

[0091] Tannic acid-modified black phosphorus, 5 parts;

[0092] 0.8 parts catalyst;

[0093] 15 parts crosslinking agent;

[0094] Six parts of silane coupling agent.

[0095] The preparation method of the aluminum phosphate-coated boron nitride composite material includes the following steps:

[0096] 10g of boron nitride nanosheets were ultrasonically dispersed in 100mL of deionized water to obtain a boron nitride nanosheet dispersion. A 30wt% hydrochloric acid solution was added dropwise to make the pH of the dispersion 2, thus obtaining dispersion A.

[0097] 0.6 g of aluminum hydroxide and 4.5 g of phosphoric acid were added to 100 mL of deionized water and stirred for 40 min to obtain solution B. Solution B was then slowly added dropwise to dispersion A and stirred vigorously for 30 min. Subsequently, 25 wt% ammonia solution was added dropwise to adjust the pH of the solution to 6. The solution was centrifuged, washed, and vacuum dried at 70 °C to constant weight to obtain aluminum phosphate-coated boron nitride composite material.

[0098] The preparation method of the tannic acid modified black phosphorus includes the following steps:

[0099] (1) Add 8g of amorphous red phosphorus and 2g of melamine to 150mL of butanediamine, and then react with solvent at 180℃ for 16h. After the reaction is completed, the product is obtained. Finally, the product is filtered, washed and dried at 90℃ for 14h to prepare the nitrogen-doped black phosphorus composite material.

[0100] (2) Disperse 10g of nitrogen-doped black phosphorus and 10g of tannic acid in 100mL of water by ultrasonication, stir at 600rpm for 1.5h, centrifuge, wash, and vacuum dry at 60℃ for 12h to obtain tannic acid modified black phosphorus.

[0101] The α,ω-dihydroxypolydimethylsiloxane has a viscosity of 20,000 cps;

[0102] The catalyst is dibutyltin dilaurate;

[0103] The crosslinking agent is propyltributylone oxime silane;

[0104] The silane coupling agent is KH550.

[0105] A method for preparing a fire-retardant sealant, wherein the preparation method is the same as in Example 1.

[0106] Comparative Example 1

[0107] The similarities between Comparative Example 1 and Example 3 will not be repeated here. The difference lies in the preparation method of the aluminum phosphate and boron nitride composite material, which includes the following steps:

[0108] 0.6 g of aluminum hydroxide and 4.5 g of phosphoric acid were added to 100 mL of deionized water and stirred for 40 min to obtain a solution. Then, 25 wt% ammonia solution was added dropwise to adjust the pH of the solution to 6. The solution was centrifuged, washed, and dried under vacuum at 70 °C to constant weight. The obtained product was then ultrasonically dispersed with 10 g of boron nitride nanosheets in 100 mL of deionized water for 30 min. The product was filtered, washed, and dried under vacuum at 70 °C to constant weight to obtain a composite material of aluminum phosphate and boron nitride.

[0109] Comparative Example 2

[0110] The similarities between Comparative Example 2 and Example 3 will not be repeated here. The difference is that boron nitride nanosheets of equal mass are used instead of aluminum phosphate coated boron nitride composite material.

[0111] Comparative Example 3

[0112] Comparative Example 3 and Example 3 are similar in that they will not be repeated here. The difference is that an equal mass of black phosphorus is used to replace the nitric acid-modified black phosphorus, and the preparation method of the black phosphorus includes the following steps:

[0113] 8g of amorphous red phosphorus and 2g of melamine were added to 150mL of butanediamine, and then the mixture was solvothermal reacted at 180℃ for 16h. After the reaction was completed, the product was obtained. Finally, the product was filtered, washed, and dried at 90℃ for 14h to prepare the nitrogen-doped black phosphorus composite material.

[0114] Comparative Example 4

[0115] Comparative Example 4 and Example 3 are similar in many ways, but differ in that an equal amount of aluminum diethylphosphonate is used to replace aluminum phosphate in the boron nitride composite material.

[0116] Comparative Example 5

[0117] The similarities between Comparative Example 5 and Example 3 will not be repeated here. The difference is that an equal amount of aluminum diethylphosphonate was used to replace the tannic acid-modified black phosphorus.

[0118] The sealants prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to performance tests. The specific test results are shown in Table 1. The test methods are as follows:

[0119] Oxygen index: Tested according to the method specified in GB / T 2406-2008;

[0120] Tensile strength: Tested according to the method specified in GB / T 528-1998.

[0121] Table 1

[0122]

[0123] By comparing the examples and comparative examples, it can be seen that the fire-retardant sealant prepared by the present invention has high flame retardant properties and tensile strength. Moreover, by comparing Example 3 with Comparative Examples 1-5, aluminum phosphate coated boron nitride has a synergistic effect. Tannic acid modification can promote the dispersion of black phosphorus while also improving the flame retardancy and smoke suppression of the sealant. Furthermore, the combination of aluminum phosphate coated boron nitride composite material and aluminum diethylphosphinate synergistically improves the flame retardant and fireproof properties of the sealant.

[0124] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A fire-retardant sealant, characterized in that: By weight, it includes the following components: 100 parts of α,ω-dihydroxypolydimethylsiloxane; 60-80 parts of trimethylpolydimethylsiloxane; 10-20 parts of aluminum phosphate-coated boron nitride composite material; 5-15 parts of aluminum diethylphosphinate; 3-7 parts of tannic acid-modified black phosphorus; Catalyst 0.5~1 part; 10-20 parts of crosslinking agent; 4-8 parts of silane coupling agent.

2. The fire-retardant sealant according to claim 1, characterized in that: The preparation method of the aluminum phosphate-coated boron nitride composite material includes the following steps: Boron nitride nanosheets were ultrasonically dispersed in deionized water to obtain a boron nitride nanosheet dispersion. Hydrochloric acid solution was added dropwise to adjust the pH of the dispersion to 2-3, resulting in dispersion A. Aluminum hydroxide and phosphoric acid were added to deionized water and stirred to obtain solution B. Solution B was then slowly added dropwise to dispersion A while stirring vigorously. Subsequently, ammonia solution was added dropwise to adjust the pH of the solution to 5-7. The solution was then centrifuged, washed, and vacuum dried to constant weight to obtain aluminum phosphate-coated boron nitride composite material.

3. The fire-retardant sealant according to claim 2, characterized in that: The concentration of the hydrochloric acid is 25-35 wt%; the mass ratio of the boron nitride nanosheets, aluminum hydroxide, and phosphoric acid is 10:0.5-0.7:4-5.

4. The fire-retardant sealant according to claim 2, characterized in that: The stirring time is 30-50 min; the concentration of ammonia water is 25 wt%; the vigorous stirring time is 25-35 min; and the vacuum drying temperature is 60-80℃.

5. The fire-retardant sealant according to claim 1, characterized in that: The preparation method of tannic acid modified black phosphorus includes the following steps: (1) Amorphous red phosphorus and nitrogen-containing compounds are added to a solvent and then subjected to a solvothermal reaction. After the reaction is completed, the product is obtained. Finally, the product is filtered, washed and dried to prepare the nitrogen-doped black phosphorus composite material. (2) The nitrogen-doped black phosphorus and tannic acid obtained in step (1) are ultrasonically dispersed in water, stirred, centrifuged, washed, and vacuum dried to obtain tannic acid-modified black phosphorus.

6. The fire-retardant sealant according to claim 5, characterized in that: In step (1), the mass ratio of amorphous red phosphorus to nitrogen-containing compound is 1:5 to 10:1; the nitrogen-containing compound is at least one of urea, thiourea and melamine; the solvent is at least one of ethylenediamine, propylenediamine and butanediamine; the solvothermal reaction conditions are 5 to 20 h at 150 to 200 °C; and the drying is 10 to 18 h at 80 to 100 °C.

7. The fire-retardant sealant according to claim 5, characterized in that: In step (2), the stirring conditions are stirring at 500~700 rpm for 1~2 hours; the vacuum drying is vacuum drying at 40~80℃ for 10~14 hours; and the mass ratio of nitrogen-doped black phosphorus to tannic acid is 1:0.8~1.

2.

8. The fire-retardant sealant according to claim 1, characterized in that: The α,ω-dihydroxypolydimethylsiloxane has a viscosity of 15000cps to 25000cps; the catalyst is dibutyltin dilaurate or dibutyltin diacetate; the crosslinking agent is methyltributanone oxime silane or propyltributanone oxime silane; and the silane coupling agent is KH550 or KH560.

9. A method for preparing a fire-retardant sealant according to any one of claims 1-8, characterized in that: The preparation method includes the following steps: (1) The α,ω-dihydroxy polydimethylsiloxane, trimethyl polydimethylsiloxane, aluminum phosphate-coated boron nitride composite material, aluminum diethylphosphonate and tannic acid-modified black phosphorus are added to a planetary machine and dehydrated for 120-200 min at a temperature of 110℃~150℃ and a vacuum degree of -0.06MPa~-0.08MPa to obtain the base material; (2) After the base material is cooled to room temperature, the crosslinking agent, silane coupling agent and catalyst are added in sequence, and the mixture is stirred for 60 to 120 minutes under a vacuum of -0.06 MPa to -0.08 MPa to obtain the fireproof and flame-retardant sealant.

10. The application of a fire-retardant sealant according to any one of claims 1-8 in the construction field.

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