Dynamically vulcanized polyurethane silicone rubber composite material and preparation method thereof

Abstract

The invention discloses a dynamically vulcanized polyurethane silicone rubber composite material and a preparation method thereof, and belongs to the technical field of high polymer materials, and the dynamically vulcanized polyurethane silicone rubber composite material comprises the following components in parts by mass: 40-50 parts of flame-retardant polyurethane particles, 50-70 parts of raw silicone rubber, 2-5 parts of hydrogen-containing silicone oil, 10-20 parts of a compatilizer and 0.1-0.2 part of a platinum catalyst, the flame-retardant polyurethane particles are prepared by mixing thermoplastic polyurethane particles and flame-retardant reinforced powder; the flame-retardant reinforced powder is prepared by mixing flame-retardant composite powder with chitosan and then mixing the mixture with montmorillonite; the organophosphorus flame retardant is coated in the reinforcing filler, so that migration of the organophosphorus flame retardant in the polyurethane silicone rubber composite material is reduced, the influence of the organophosphorus flame retardant on the mechanical property of the polyurethane silicone rubber composite material is reduced, and the flame retardant property is improved; and montmorillonite and silicon dioxide as carriers can be used as reinforcing fillers to improve the mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a dynamically vulcanized polyurethane silicone rubber composite material and its preparation method. Background Technology

[0002] Dynamic vulcanization involves melting and blending unvulcanized raw rubber with non-vulcanizable thermoplastic polymers in a high-temperature, high-shear blending device, while simultaneously vulcanizing the rubber phase under the action of a crosslinking agent. This results in a structure where micron-sized vulcanized rubber particles are uniformly dispersed in the resin. After crosslinking, the high-temperature permanent deformation rate decreases, and the oil resistance is significantly enhanced (e.g., the NBR / PA system exhibits excellent solvent resistance). Tensile strength and elongation at break increase with increasing degree of crosslinking.

[0003] Polyether-type TPU is widely used in cable sheathing, automotive parts and other fields due to its good toughness, resilience, low temperature resistance and hydrolysis resistance. However, the oxygen index of polyether-type TPU is only about 18%, which makes it a flammable material. When burning, it produces a fierce flame with thick black smoke and severe dripping. Adding flame retardants to polyether-type TPU to improve its flame retardant performance has obvious advantages such as simple operation and low cost. However, to achieve a high flame retardant effect, the amount of flame retardant added must be increased. However, adding a large amount of flame retardant will reduce the physical and mechanical properties of polyether-type TPU.

[0004] Chinese invention patent application CN109593349A discloses a flame-retardant thermoplastic dynamic vulcanized silicone rubber and its preparation method. The method involves dynamically vulcanizing a mixture of thermoplastic polyurethane elastomer, silicone rubber compound, flame retardant, crosslinking agent, compatibilizer, and catalyst to prepare the flame-retardant thermoplastic dynamic vulcanized silicone rubber, thereby improving the flame-retardant properties of the rubber. However, the flame retardant used in this method is an organophosphorus flame retardant, which generates gases that pollute the environment. Furthermore, the flame retardant is prone to migration in the matrix, affecting the mechanical and flame-retardant properties of the composite material. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of how to reduce the migration of organophosphorus flame retardants and improve the mechanical and flame retardant properties of polyurethane silicone rubber composites, and to provide a dynamically vulcanized polyurethane silicone rubber composite and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions: A dynamically vulcanized polyurethane silicone rubber composite material, comprising the following components by weight: 40-50 parts flame-retardant polyurethane granules, 50-70 parts raw silicone rubber, 2-5 parts hydrogen-containing silicone oil, 10-20 parts compatibilizer and 0.1-0.2 parts platinum catalyst.

[0007] The compatibilizer is one of ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer, and ethylene-vinyl acetate copolymer.

[0008] Flame-retardant polyurethane particles are made by mixing thermoplastic polyurethane particles with flame-retardant reinforcing powder.

[0009] Flame-retardant reinforced powder is prepared by mixing flame-retardant composite powder with chitosan and then with montmorillonite.

[0010] The flame-retardant composite powder is prepared by mixing Fe-MOF / silica composite powder with diphenylphosphine.

[0011] Furthermore, the flame-retardant polyurethane particles are specifically prepared by the following steps: In a mixer, dried thermoplastic polyurethane granules are stirred and melted at 180-185℃ and 70-80 rpm. Flame-retardant reinforcing powder is added and the mixture is stirred and mixed for 20-30 minutes. The mixture is then extruded and granulated to obtain flame-retardant polyurethane granules.

[0012] Furthermore, the mass ratio of thermoplastic polyurethane particles to flame-retardant reinforcing powder is 20-25:4-6.

[0013] Furthermore, the flame-retardant reinforcing powder is prepared by the following steps: In a reaction vessel, the flame-retardant composite powder is ultrasonically dispersed in deionized water. A 1-1.5 wt% chitosan solution is added dropwise to the reaction vessel and stirred for 30-40 min. The precipitate is collected by centrifugation, washed, and then dispersed again in deionized water. A 1 wt% montmorillonite dispersion is added dropwise. After the addition is complete, the mixture is stirred for 30-40 min, the precipitate is collected by centrifugation, washed, and then vacuum dried for 10-12 h. Finally, the precipitate is pulverized and passed through a 400-mesh sieve to obtain the flame-retardant reinforced powder.

[0014] Furthermore, the ratio of flame-retardant composite powder, deionized water, chitosan solution and montmorillonite dispersion is 8-12g: 400-500mL: 80-120mL: 120-150mL.

[0015] Furthermore, the flame-retardant composite powder is prepared by the following steps: Fe-MOF / silica composite powder, paraformaldehyde and methanol were mixed in a reaction vessel and stirred for 30-40 min. Diphenylphosphine methanol solution was added dropwise to the reaction vessel, and then heated to 60-65℃ for 6-8 h. The precipitate was collected by centrifugation, washed and dried under vacuum to obtain flame-retardant composite powder.

[0016] Furthermore, the ratio of Fe-MOF / silica composite powder, paraformaldehyde, methanol, and diphenylphosphine methanol solution is 8-12g: 2-2.5g: 150-200mL: 70-75mL; the diphenylphosphine methanol solution is prepared by mixing diphenylphosphine and methanol in a ratio of 2-2.2g: 20-25mL.

[0017] Furthermore, the Fe-MOF / silica composite powder is specifically prepared by the following steps: Porous silica was added to DMF in a reaction vessel and stirred for 30-40 min. Then, ferric chloride hexahydrate and 2-aminoterephthalic acid were added and stirred until dissolved. The mixture was then heated to 120-130℃ and reacted for 10-12 h. The precipitate was collected by centrifugation, washed, and dried under vacuum to obtain Fe-MOF / silica composite powder.

[0018] Furthermore, the ratio of porous silica, DMF, ferric chloride hexahydrate, and 2-aminoterephthalic acid is 8-12g: 300-400mL: 3.2-4.8g: 4-5.5g.

[0019] A method for preparing a dynamically vulcanized polyurethane silicone rubber composite material, the method comprising the following steps: Flame-retardant polyurethane particles, raw silicone rubber, hydrogen-containing silicone oil, and compatibilizer are melt-blended in an internal mixer at a temperature of 180-190℃ and a speed of 60-80 rpm for 5-10 minutes. The mixture is then extruded and granulated to obtain a premix. The premix is ​​then mixed with a platinum catalyst and fed into a twin-screw extruder for dynamic vulcanization at a temperature of 190-210℃ and a speed of 200-300 rpm for 10-15 minutes. The resulting polyurethane-silicone rubber composite material is then extruded.

[0020] The beneficial effects of this invention are: 1. The polyurethane silicone rubber composite material prepared by the present invention reduces the migration of organophosphorus flame retardants in the polyurethane silicone rubber composite material by coating organophosphorus flame retardants in the reinforcing filler, and also reduces the influence of organophosphorus flame retardants on the mechanical properties of the polyurethane silicone rubber composite material, thereby improving the flame retardant properties of the polyurethane silicone rubber composite material. Furthermore, montmorillonite and silica, which serve as carriers, can also serve as reinforcing fillers to improve the mechanical properties of the polyurethane silicone rubber composite material.

[0021] 2. The preparation method of the present invention synthesizes Fe-MOF with smaller porous structure in situ on porous silica, which promotes the formation of carbon layer and improves flame retardant performance. At the same time, it imparts amino groups to porous silica, which facilitates grafting and bonding with diphenylphosphine. By utilizing the physical adsorption capacity and grafting force of the porous structure, the flame retardant diphenylphosphine is fixed in the Fe-MOF / silica composite powder, resulting in a composite powder with good flame retardant performance.

[0022] 3. The preparation method of the present invention involves adhering chitosan to the surface of flame-retardant composite powder and using the attraction between the positive charge on the surface of chitosan and the negative charge on the surface of montmorillonite to assemble a core-shell composite powder with montmorillonite as the shell and flame-retardant composite powder as the core. The coating of chitosan and montmorillonite reduces the migration of diphenylphosphine in the flame-retardant composite powder and improves the flame-retardant performance. Furthermore, montmorillonite can also be used as a reinforcing filler to improve the mechanical properties of polyurethane silicone rubber composite materials. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments in the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: A method for preparing a dynamically vulcanized polyurethane silicone rubber composite material, comprising the following steps: S1. Add 8g of porous silica to 300mL of DMF in a reaction vessel, stir for 30min, then add 3.2g of ferric chloride hexahydrate and 4g of 2-aminoterephthalic acid, stir to dissolve, heat to 120℃ and react for 10h, cool and centrifuge to collect the precipitate, wash the precipitate with DMF, ethanol and deionized water, and vacuum dry at 60℃ for 10h to obtain Fe-MOF / silica composite powder.

[0025] S2. In a reaction vessel, 8g of Fe-MOF / silica composite powder, 2g of paraformaldehyde and 150mL of methanol are mixed and stirred for 30min. Diphenylphosphine and methanol are mixed at a ratio of 2g:20mL to prepare a diphenylphosphine methanol solution. 70mL of the diphenylphosphine methanol solution is added dropwise to the reaction vessel, and then heated to 60℃ for 6h. The precipitate is collected by centrifugation, washed with deionized water, and vacuum dried for 10h to obtain the flame-retardant composite powder.

[0026] S3. In a reaction vessel, 8g of flame-retardant composite powder was ultrasonically dispersed in 400mL of deionized water. Chitosan was dissolved in 1wt% acetic acid aqueous solution to prepare a 1wt% chitosan solution. 80mL of chitosan solution was added dropwise to the reaction vessel and stirred for 30min. The precipitate was collected by centrifugation and washed with deionized water. The precipitate was then dispersed again in 400mL of deionized water. 120mL of 1wt% montmorillonite dispersion was added dropwise. After the addition was complete, the mixture was stirred for 30min. The precipitate was collected by centrifugation and washed with deionized water. The precipitate was then vacuum dried at 80℃ for 10h and then pulverized through a 400-mesh sieve to obtain flame-retardant reinforced powder.

[0027] S4. In a mixer, 40g of dried thermoplastic polyurethane granules are stirred and melted at 180℃ and 70rpm. 8g of flame-retardant reinforcing powder is added and the mixture is stirred and mixed for 20min. The mixture is then extruded and granulated to obtain flame-retardant polyurethane granules.

[0028] S5. In a Banbury mixer, 40g of flame-retardant polyurethane granules, 50g of raw silicone rubber, 2g of hydrogen-containing silicone oil and 10g of ethylene-acrylic acid copolymer are melt-blended at a mixing temperature of 180℃ and a speed of 60rpm for 5min. Then, the mixture is extruded and granulated to obtain a premix. The premix is ​​mixed with 0.1g of platinum catalyst and then added to a twin-screw extruder for dynamic vulcanization reaction at a vulcanization temperature of 190℃ and a speed of 200rpm for 10min. The resulting polyurethane-silicone rubber composite material is then extruded.

[0029] Example 2: A method for preparing a dynamically vulcanized polyurethane silicone rubber composite material, comprising the following steps: S1. In a reaction vessel, 10g of porous silica was added to 350mL of DMF and stirred for 35min. Then, 4g of ferric chloride hexahydrate and 4.75g of 2-aminoterephthalic acid were added and stirred until dissolved. The mixture was heated to 125℃ and reacted for 11h. After cooling, the precipitate was collected by centrifugation. The precipitate was washed with DMF, ethanol and deionized water and dried under vacuum at 65℃ for 11h to obtain Fe-MOF / silica composite powder.

[0030] S2. In a reaction vessel, 10g of Fe-MOF / silica composite powder, 2.25g of paraformaldehyde and 175mL of methanol are mixed and stirred for 35min. Diphenylphosphine and methanol are mixed at a ratio of 2.1g:22.5mL to prepare a diphenylphosphine methanol solution. 72.5mL of the diphenylphosphine methanol solution is added dropwise to the reaction vessel, and then heated to 62.5℃ for 7h. The precipitate is collected by centrifugation, washed with deionized water, and vacuum dried for 11h to obtain the flame-retardant composite powder.

[0031] S3. In a reaction vessel, 10g of flame-retardant composite powder was ultrasonically dispersed in 450mL of deionized water. Chitosan was dissolved in 1wt% acetic acid aqueous solution to prepare a 1.25wt% chitosan solution. 100mL of chitosan solution was added dropwise to the reaction vessel and stirred for 35min. The precipitate was collected by centrifugation and washed with deionized water. The precipitate was then dispersed again in 475mL of deionized water. 135mL of 1wt% montmorillonite dispersion was added dropwise. After the addition was complete, the mixture was stirred for 35min and the precipitate was collected by centrifugation. The precipitate was washed with deionized water and vacuum dried at 82.5℃ for 11h. Then, the powder was pulverized and passed through a 400-mesh sieve to obtain flame-retardant reinforced powder.

[0032] S4. In a mixer, 45g of dried thermoplastic polyurethane granules are stirred and melted at 182.5℃ and 75rpm. 10g of flame-retardant reinforcing powder is added and the mixture is stirred and mixed for 25min. The mixture is then extruded and granulated to obtain flame-retardant polyurethane granules.

[0033] S5. In a Banbury mixer, 45g of flame-retardant polyurethane granules, 60g of silicone rubber raw rubber, 3.5g of hydrogen-containing silicone oil and 15g of ethylene methyl acrylate copolymer are melt-blended at a mixing temperature of 185℃ and a speed of 70rpm for 7.5min. The mixture is then extruded and granulated to obtain a premix. The premix is ​​mixed with 0.15g of platinum catalyst and then added to a twin-screw extruder for dynamic vulcanization at a vulcanization temperature of 200℃ and a speed of 250rpm for 12.5min. The resulting polyurethane silicone rubber composite material is then extruded.

[0034] Example 3: A method for preparing a dynamically vulcanized polyurethane silicone rubber composite material, comprising the following steps: S1. In a reaction vessel, 12g of porous silica was added to 400mL of DMF and stirred for 40min. Then, 4.8g of ferric chloride hexahydrate and 5.5g of 2-aminoterephthalic acid were added and stirred until dissolved. The mixture was heated to 130℃ and reacted for 12h. After cooling, the precipitate was collected by centrifugation. The precipitate was washed with DMF, ethanol and deionized water and dried under vacuum at 70℃ for 12h to obtain Fe-MOF / silica composite powder.

[0035] Fe-MOF with a porous structure is generated in situ on the surface and inside of porous silica. Using 2-aminoterephthalic acid as a ligand, amino groups are given to the porous silica. Furthermore, the finer porous structure in Fe-MOF is beneficial for flame retardants to promote the formation of a carbon layer and improve flame retardant performance.

[0036] S2. In a reaction vessel, 12g of Fe-MOF / silica composite powder, 2.5g of paraformaldehyde and 200mL of methanol are mixed and stirred for 40min. Diphenylphosphine and methanol are mixed at a ratio of 2.2g:25mL to prepare a diphenylphosphine methanol solution. 75mL of the diphenylphosphine methanol solution is added dropwise to the reaction vessel, and then heated to 65℃ for 8h. The precipitate is collected by centrifugation, washed with deionized water, and vacuum dried for 12h to obtain the flame-retardant composite powder.

[0037] First, by utilizing the physical adsorption properties of the porous structure of Fe-MOF / silica composite powder, diphenylphosphine is adsorbed within the pore structure of the Fe-MOF / silica composite powder. Then, taking advantage of the nucleophilicity of the P-H bond in diphenylphosphine, it undergoes a grafting reaction with the amino group in the Fe-MOF ligand to form a P-N bond, thereby fixing the flame retardant diphenylphosphine in the Fe-MOF / silica composite powder, resulting in a composite reinforcing filler with flame retardant capabilities.

[0038] S3. In a reaction vessel, 12g of flame-retardant composite powder was ultrasonically dispersed in 500mL of deionized water. Chitosan was dissolved in 1wt% acetic acid aqueous solution to prepare a 1.5wt% chitosan solution. 120mL of chitosan solution was added dropwise to the reaction vessel and stirred for 40min. The precipitate was collected by centrifugation and washed with deionized water. The precipitate was then dispersed again in 550mL of deionized water. 150mL of 1wt% montmorillonite dispersion was added dropwise. After the addition was complete, the mixture was stirred for 40min. The precipitate was collected by centrifugation and washed with deionized water. The precipitate was then vacuum dried at 85℃ for 12h and then pulverized through a 400-mesh sieve to obtain flame-retardant reinforced powder.

[0039] By adhering chitosan to the surface of flame-retardant composite powder and using the attraction between the positive charge on the surface of chitosan and the negative charge on the surface of montmorillonite, a core-shell composite powder with montmorillonite as the shell and flame-retardant composite powder as the core is obtained. The coating of chitosan and montmorillonite reduces the migration of diphenylphosphine in the flame-retardant composite powder, thereby improving the flame-retardant performance. Furthermore, montmorillonite can also be used as a reinforcing filler to improve the mechanical properties of polyurethane silicone rubber composites.

[0040] S4. In a mixer, 50g of dried thermoplastic polyurethane granules are stirred and melted at 185℃ and 80rpm. 12g of flame-retardant reinforcing powder is added and the mixture is stirred and mixed for 30min. The mixture is then extruded and granulated to obtain flame-retardant polyurethane granules.

[0041] S5. In a Banbury mixer, 50g of flame-retardant polyurethane granules, 70g of raw silicone rubber, 5g of hydrogen-containing silicone oil, and 20g of ethylene-vinyl acetate copolymer are melt-blended at 190℃ and 80rpm for 10min. The resulting mixture is then extruded and granulated to obtain a premix. This premix is ​​then mixed with 0.2g of platinum-based catalyst and added to a twin-screw extruder for dynamic vulcanization at 210℃ and 300rpm for 15min. The resulting polyurethane-silicone rubber composite material is then extruded. Comparative Example 1: The difference from Example 1 is that in S2, Fe-MOF / silica composite powder was replaced with an equal mass of porous silica, while the other steps remained unchanged, and a polyurethane silicone rubber composite material was obtained.

[0042] Comparative Example 2: The difference from Example 1 is that in S3, 3g of diphenylphosphine and 5g of porous silica were used to replace the flame-retardant composite powder, while the other steps remained unchanged, and a polyurethane silicone rubber composite material was obtained.

[0043] Comparative Example 3: The difference from Example 1 is that in S4, flame-retardant reinforcing powder is replaced with flame-retardant composite powder of equal mass, while the other steps remain unchanged, and polyurethane silicone rubber composite material is obtained.

[0044] The porous silica particles, with a diameter of 1-2 μm, were purchased from Jiangsu Xianfeng Nanotechnology Co., Ltd.

[0045] Paraformaldehyde was purchased from Sigma-Aldrich.

[0046] The thermoplastic polyurethane granules have a Shore hardness of 72A and are designated as TPU 1170AU.

[0047] The polyurethane silicone rubber composites prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. Tensile strength, elongation at break, and right-angle tear strength were tested according to standards GB / T528 and GB / T529. Vertical flammability was tested according to standard GB / T 10707. After hot air aging tests according to standard GB / T3512, the vertical flammability was further tested. The results are shown in Table 1. Table 1: Performance Test Results project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength (MPa) 16.2 16.5 16.6 15.9 12.4 15.3 Elongation at break (%) 485 489 491 478 413 462 Tear strength (kN / m) 49 51 52 47 35 44 Vertical flammability rating FV-0 FV-0 FV-0 FV-1 FV-1 FV-0 Vertical combustion rating after aging FV-0 FV-0 FV-0 FV-1 FV-1 FV-1 As can be seen from Table 1, the polyurethane silicone rubber composite material prepared by the present invention has excellent mechanical properties and good flame retardant properties. After aging treatment, the migration of organophosphorus flame retardants in the polyurethane silicone rubber composite material is small, and the flame retardant properties are good.

[0048] Comparative Example 1, due to the absence of Fe-MOF synthesis on the porous silica surface, reduced the porous structure, decreased the specific surface area, and reduced the composite strength of diphenylphosphine and porous silica. The flame retardant migrated during the preparation process, and the migration increased after aging treatment, resulting in a decrease in flame retardant performance.

[0049] In Comparative Example 2, the dispersion of the flame-retardant reinforcing powder in the thermoplastic polyurethane particles was reduced due to the coating of diphenylphosphine and porous silica with chitosan and the composite with montmorillonite. As a result, the mechanical strength of the polyurethane silicone rubber composite material was lower, and the synergistic effect between the flame retardant diphenylphosphine and porous silica was reduced, thus weakening the flame-retardant performance.

[0050] Comparative Example 3, because it did not use chitosan and montmorillonite to coat the composite reinforcing filler, could not protect the diphenylphosphine on the composite reinforcing filler, and the mechanical properties were reduced, resulting in an increase in the migration of diphenylphosphine after aging treatment and a decrease in flame retardant properties after aging.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A dynamically vulcanized polyurethane silicone rubber composite material, characterized in that, By mass, it contains the following components: 40-50 parts flame-retardant polyurethane granules, 50-70 parts raw silicone rubber, 2-5 parts hydrogen-containing silicone oil, 10-20 parts compatibilizer and 0.1-0.2 parts platinum-based catalyst; The compatibilizer is one of ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer, and ethylene-vinyl acetate copolymer; The flame-retardant polyurethane particles are prepared by mixing thermoplastic polyurethane particles with flame-retardant reinforcing powder. The flame-retardant reinforced powder is prepared by mixing flame-retardant composite powder with chitosan and then with montmorillonite. The flame-retardant composite powder is prepared by mixing Fe-MOF / silica composite powder with diphenylphosphine.

2. The dynamically vulcanized polyurethane silicone rubber composite material according to claim 1, characterized in that, The flame-retardant polyurethane particles are specifically prepared by the following steps: In a mixer, dried thermoplastic polyurethane granules are stirred and melted at 180-185℃ and 70-80 rpm. Flame-retardant reinforcing powder is added and the mixture is stirred and mixed for 20-30 minutes. The mixture is then extruded and granulated to obtain flame-retardant polyurethane granules.

3. The dynamically vulcanized polyurethane silicone rubber composite material according to claim 2, characterized in that, The mass ratio of the thermoplastic polyurethane particles to the flame-retardant reinforcing powder is 20-25:4-6.

4. The dynamically vulcanized polyurethane silicone rubber composite material according to claim 3, characterized in that, The flame-retardant reinforced powder is specifically prepared by the following steps: In a reaction vessel, the flame-retardant composite powder is ultrasonically dispersed in deionized water. A 1-1.5 wt% chitosan solution is added dropwise to the reaction vessel and stirred for 30-40 min. The precipitate is collected by centrifugation, washed, and then dispersed again in deionized water. A 1 wt% montmorillonite dispersion is added dropwise. After the addition is complete, the mixture is stirred for 30-40 min, the precipitate is collected by centrifugation, washed, and then vacuum dried for 10-12 h. Finally, the precipitate is pulverized and passed through a 400-mesh sieve to obtain the flame-retardant reinforced powder.

5. The dynamically vulcanized polyurethane silicone rubber composite material according to claim 4, characterized in that, The ratio of the amount of flame-retardant composite powder, deionized water, chitosan solution and montmorillonite dispersion is 8-12g: 400-500mL: 80-120mL: 120-150mL.

6. The dynamically vulcanized polyurethane silicone rubber composite material according to claim 5, characterized in that, The flame-retardant composite powder is specifically prepared by the following steps: Fe-MOF / silica composite powder, paraformaldehyde and methanol were mixed in a reaction vessel and stirred for 30-40 min. Diphenylphosphine methanol solution was added dropwise to the reaction vessel, and then heated to 60-65℃ for 6-8 h. The precipitate was collected by centrifugation, washed and dried under vacuum to obtain flame-retardant composite powder.

7. The dynamically vulcanized polyurethane silicone rubber composite material according to claim 6, characterized in that, The ratio of Fe-MOF / silica composite powder, paraformaldehyde, methanol, and diphenylphosphine methanol solution is 8-12g: 2-2.5g: 150-200mL: 70-75mL; the diphenylphosphine methanol solution is prepared by mixing diphenylphosphine and methanol in a ratio of 2-2.2g: 20-25mL.

8. The dynamically vulcanized polyurethane silicone rubber composite material according to claim 7, characterized in that, The Fe-MOF / silica composite powder is specifically prepared by the following steps: Porous silica was added to DMF in a reaction vessel and stirred for 30-40 min. Then, ferric chloride hexahydrate and 2-aminoterephthalic acid were added and stirred until dissolved. The mixture was then heated to 120-130℃ and reacted for 10-12 h. The precipitate was collected by centrifugation, washed, and dried under vacuum to obtain Fe-MOF / silica composite powder.

9. The dynamically vulcanized polyurethane silicone rubber composite material according to claim 8, characterized in that, The ratio of porous silica, DMF, ferric chloride hexahydrate and 2-aminoterephthalic acid is 8-12g: 300-400mL: 3.2-4.8g: 4-5.5g.

10. The method for preparing a dynamically vulcanized polyurethane silicone rubber composite material according to claim 1, characterized in that, The preparation method includes the following steps: Flame-retardant polyurethane particles, raw silicone rubber, hydrogen-containing silicone oil, and compatibilizer are melt-blended in an internal mixer at a temperature of 180-190℃ and a speed of 60-80 rpm for 5-10 minutes. The mixture is then extruded and granulated to obtain a premix. The premix is ​​then mixed with a platinum catalyst and fed into a twin-screw extruder for dynamic vulcanization at a temperature of 190-210℃ and a speed of 200-300 rpm for 10-15 minutes. The resulting polyurethane-silicone rubber composite material is then extruded.