Composite material applied to underground rail transit and preparation method thereof

Abstract

The invention relates to the technical field of materials, and discloses a composite material applied to underground rail transit and a preparation method thereof.The preparation method comprises the steps that bentonite, hydroxylated bentonite, modified polyurethane, red mud, biotite and epoxidized triazinyl bentonite are added into a reactor, stirred and mixed into slurry, then the slurry is added into a mold, a temperature rise reaction is conducted, and the composite material is obtained; the composite material applied to underground rail transit is obtained. In the stirring process, hydroxyl groups in the modified polyurethane and the hydroxylated bentonite react with epoxy groups in the epoxidized triazinyl bentonite, cross-linking is generated between the modified polyurethane and the hydroxylated bentonite and a tight cross-linked network is formed, so that the connection is tighter, and the stretching effect is improved; and meanwhile, the compatibility among the components is also increased, so that the components are more uniformly distributed in the material. Phosphorus and triazinyl in the modified polyurethane and the hydroxylated bentonite also have good flame retardant effects, and form an inorganic-organic flame retardant composite system with the inorganic bentonite.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and in particular to a composite material used in underground rail transportation and a preparation method thereof. Background Art

[0002] In recent years, the construction of urban rail transit projects in my country has entered a period of rapid development, and the market demand for urban rail transit vehicles has been increasing. However, during use, it will be flammable when encountering a fire, which will affect its normal use; if the tensile resistance is not good, it will also affect its normal use. Therefore, the performance requirements for composite materials used in underground rail transit are getting higher and higher. For example, patent CN114737088B discloses a lightweight high-entropy composite material for rail transit and a preparation method thereof. The invention discloses a lightweight high-entropy composite material prepared by semi-solid die casting, which has small shrinkage, low looseness and shrinkage rate, and its reinforcement is well combined with the matrix, and the comprehensive mechanical properties are high, but its flame retardant effect has not been improved. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] In view of the deficiencies in the prior art, the present invention provides a composite material for underground rail transit and a preparation method thereof, which has good flame retardant and tensile effects.

[0005] (II) Technical solution

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a composite material for underground rail transit, comprising the following components by weight: 60-80 parts by weight of bentonite, 15-25 parts by weight of hydroxylated bentonite, 4-6 parts by weight of modified polyurethane, 10-14 parts by weight of red mud, 6-8 parts by weight of biotite, and 4-10 parts by weight of epoxidized triazine bentonite.

[0007] Preferably, the preparation method of the phosphorus-modified polyurethane is:

[0008] (1) Add 2,2-bis(bromomethyl)-1,3-propanediol and 2,6-dialdehyde-1,5-dihydroxynaphthalene to an acetone solvent, stir evenly, then continue to add a 3-5 mol / L sodium hydroxide aqueous solution, react at 65-85° C. for 4-6 hours, and after the reaction is completed, neutralize, concentrate, filter, wash and dry to obtain an intermediate 1;

[0009] (2) adding the intermediate 1, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone to a reactor containing an ethanol solvent, stirring evenly, introducing nitrogen protection, reacting at 40-65° C. for 2-4 hours, and then continuing to add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and continuing to react at 50-70° C. for 3-5 hours. After the reaction is completed, cooling, suction filtering and drying are performed to obtain a phosphorus-containing benzene sulfone chain extender;

[0010] (3) Under nitrogen protection, polyether polyol and hexamethylene diisocyanate are added to a reactor and stirred evenly, and then dibutyltin dilaurate catalyst is added thereto, and the reaction is carried out at 60-75° C. for 2-4 hours, and then phosphorus-containing benzene sulfone chain extender is added thereto, and the reaction is carried out at 40-65° C. for 1-2 hours. After the reaction is completed, the reaction is cooled and discharged to obtain a modified polyurethane.

[0011] Preferably, the mass ratio of 2,2-bis(bromomethyl)-1,3-propanediol to 2,6-dialdehyde-1,5-dihydroxynaphthalene in (1) is 1:2.1-2.3.

[0012] Preferably, in the method (2), the mass ratio of the intermediate 1, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 0.8-1.2:1:1.3-2.5.

[0013] Preferably, the mass ratio of the polyether polyol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and phosphorus-containing phenylsulfone chain extender in (3) is 1.2-1.3:1:0.01-0.03:0.5-0.8.

[0014] Preferably, the preparation method of the epoxidized triazine bentonite is:

[0015] S1. Add 5-10 parts by weight of hydroxylated bentonite and 2-4 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stir and mix, react at 95-115°C for 8-12h, and then distill under reduced pressure, filter and dry to obtain olefinated bentonite;

[0016] S2. Add olefinated bentonite to N,N-dimethylformamide solvent, stir evenly, then add aqueous hydrogen peroxide solution, react at 32-45°C for 4-5h, and then distill under reduced pressure, filter and dry to obtain epoxidized triazine bentonite.

[0017] Preferably, the mass ratio of olefinated bentonite to aqueous hydrogen peroxide solution in S2 is 1:2.2-2.6.

[0018] Preferably, the preparation method of the composite material for underground rail transit is as follows: bentonite, hydroxylated bentonite, modified polyurethane, red mud, biotite, and epoxidized triazine bentonite are added to a reactor, stirred for 20-40 minutes, mixed into a slurry, and then added to a mold, reacted at 150-180°C for 1-2 hours, cooled after reaction, and obtained a composite material for underground rail transit.

[0019] Preferably, the composite material for underground rail transit is used in a substrate having a flexible display layer embedded therein.

[0020] (III) Beneficial technical effects

[0021] The present invention adds bentonite, hydroxylated bentonite, modified polyurethane, red mud, biotite and epoxidized triazine bentonite into a reactor, stirs and mixes into slurry, then adds the slurry into a mold and heats the mixture for reaction to obtain a composite material for underground rail transportation.

[0022] During the stirring process, the hydroxyl groups in the modified polyurethane and hydroxylated bentonite react with the epoxy groups in the epoxidized triazine bentonite, cross-linking each other and forming a tight cross-linking network, making the connection tighter and increasing its stretching effect; at the same time, it also increases the compatibility between each other, making it more evenly distributed in the material. The phosphorus element and triazine group in the modified polyurethane and hydroxylated bentonite also have good flame retardant effects, and form an inorganic-organic flame retardant composite system with inorganic bentonite. DETAILED DESCRIPTION

[0023] KH560 modified bentonite was prepared according to the literature "Adsorption performance of tetraethylenepentamine-grafted bentonite on acid red GR" (Chemical Industry Progress, Vol. 40, No. 5, 2021):

[0024] Add 2 g of bentonite to 100 mL of 7% hydrochloric acid solution, heat and reflux at 80°C for acidification, filter, wash with deionized water and dry to obtain acid-modified bentonite. Disperse 2 g of acid-modified bentonite in 150 mL of ethanol, add 8 g of γ-glycidyloxypropyltrimethoxysilane, stir and reflux at 90°C in a nitrogen atmosphere for 24 hours, filter, wash with ethanol and dry to obtain γ-glycidyloxypropyltrimethoxysilane-modified bentonite.

[0025] 10 g of γ-glycidyloxypropyltrimethoxysilane modified bentonite was added into a 2% sulfuric acid solution, and the mixture was stirred at 50° C. for 18 h. After the reaction was completed, the mixture was filtered, washed and dried to obtain hydroxylated bentonite.

[0026] Example 1

[0027] (1) adding 2,2-bis(bromomethyl)-1,3-propanediol and 2,6-dialdehyde-1,5-dihydroxynaphthalene to an acetone solvent, wherein the mass ratio of 2,2-bis(bromomethyl)-1,3-propanediol to 2,6-dialdehyde-1,5-dihydroxynaphthalene is 1:2.1, stirring evenly, then continuously adding 3 mol / L sodium hydroxide aqueous solution, reacting at 65° C. for 4 h, and after the reaction is completed, neutralizing, concentrating, filtering, washing and drying to obtain an intermediate 1;

[0028] (2) adding the intermediate 1 and 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone to a reactor containing an ethanol solvent, stirring evenly, introducing nitrogen protection, reacting at 40° C. for 2 h, and then continuing to add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, wherein the mass ratio of the intermediate 1, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 0.8:1:1.3, and continuing to react at 50° C. for 3 h. After the reaction is completed, cooling, suction filtering and drying are performed to obtain a phosphorus-containing benzene sulfone chain extender;

[0029] (3) under nitrogen protection, adding polyether polyol and hexamethylene diisocyanate into a reactor, stirring evenly, then adding dibutyltin dilaurate catalyst thereto, reacting at 60° C. for 2 h, then adding phosphorus-containing benzene sulfone chain extender, wherein the mass ratio of polyether polyol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and phosphorus-containing benzene sulfone chain extender is 1.2:1:0.01:0.5, reacting at 40° C. for 1 h, cooling after the reaction, discharging, and obtaining modified polyurethane;

[0030] (4) adding 5 parts by weight of hydroxylated bentonite and 2 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stirring and mixing, reacting at 95° C. for 8 h, and then distilling under reduced pressure, filtering and drying to obtain olefinated bentonite;

[0031] (5) adding olefinic bentonite to N,N-dimethylformamide solvent, stirring evenly, and then adding aqueous hydrogen peroxide solution thereto, wherein the mass ratio of olefinic bentonite to aqueous hydrogen peroxide solution is 1:2.2, reacting at 32° C. for 4 h, and then distilling under reduced pressure, filtering and drying to obtain epoxidized triazine bentonite;

[0032] (6) 60 parts by weight of bentonite, 15 parts by weight of hydroxylated bentonite, 4 parts by weight of modified polyurethane, 10 parts by weight of red mud, 6 parts by weight of biotite, and 4 parts by weight of epoxidized triazine bentonite were added into a reactor and stirred for 20 minutes to form a slurry, which was then added into a mold and reacted at 150° C. for 1 hour. After reaction, the mixture was cooled to obtain a composite material for underground rail transit.

[0033] Example 2

[0034] (1) adding 2,2-bis(bromomethyl)-1,3-propanediol and 2,6-dialdehyde-1,5-dihydroxynaphthalene to an acetone solvent, wherein the mass ratio of 2,2-bis(bromomethyl)-1,3-propanediol to 2,6-dialdehyde-1,5-dihydroxynaphthalene is 1:2.3, stirring evenly, then continuously adding 5 mol / L sodium hydroxide aqueous solution, reacting at 85° C. for 6 h, and after the reaction is completed, neutralizing, concentrating, filtering, washing and drying to obtain an intermediate 1;

[0035] (2) adding the intermediate 1 and 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone to a reactor containing an ethanol solvent, stirring evenly, introducing nitrogen protection, reacting at 65° C. for 4 hours, and then continuing to add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, wherein the mass ratio of the intermediate 1, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1.2:1:2.5, and continuing to react at 70° C. for 5 hours. After the reaction is completed, cooling, suction filtering and drying are performed to obtain a phosphorus-containing benzene sulfone chain extender;

[0036] (3) Under nitrogen protection, polyether polyol and hexamethylene diisocyanate are added to a reactor, stirred evenly, and then dibutyltin dilaurate catalyst is added thereto, reacted at 75° C. for 4 hours, and then phosphorus-containing benzene sulfone chain extender is added, wherein the mass ratio of polyether polyol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and phosphorus-containing benzene sulfone chain extender is 1.3:1:0.03:0.8, reacted at 65° C. for 2 hours, and after the reaction is completed, cooled and discharged to obtain modified polyurethane;

[0037] (4) adding 10 parts by weight of hydroxylated bentonite and 4 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stirring and mixing, reacting at 115° C. for 12 hours, and then distilling under reduced pressure, filtering and drying to obtain olefinated bentonite;

[0038] (5) adding olefinic bentonite to N,N-dimethylformamide solvent, stirring evenly, and then adding aqueous hydrogen peroxide solution thereto, wherein the mass ratio of olefinic bentonite to aqueous hydrogen peroxide solution is 1:2.6, reacting at 45° C. for 5 h, and then performing reduced pressure distillation after completion, filtering and drying to obtain epoxidized triazine bentonite;

[0039] (6) 80 parts by weight of bentonite, 25 parts by weight of hydroxylated bentonite, 6 parts by weight of modified polyurethane, 14 parts by weight of red mud, 8 parts by weight of biotite, and 10 parts by weight of epoxidized triazine bentonite were added into a reactor and stirred for 40 minutes to form a slurry, which was then added into a mold and reacted at 180° C. for 2 hours. After reaction, the mixture was cooled to obtain a composite material for underground rail transit.

[0040] Example 3

[0041] (1) adding 2,2-bis(bromomethyl)-1,3-propanediol and 2,6-dialdehyde-1,5-dihydroxynaphthalene to an acetone solvent, wherein the mass ratio of 2,2-bis(bromomethyl)-1,3-propanediol to 2,6-dialdehyde-1,5-dihydroxynaphthalene is 1:2.2, stirring evenly, then continuously adding 4 mol / L sodium hydroxide aqueous solution, reacting at 70° C. for 5 h, and after the reaction is completed, neutralizing, concentrating, filtering, washing and drying to obtain an intermediate 1;

[0042] (2) adding the intermediate 1 and 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone to a reactor containing an ethanol solvent, stirring evenly, introducing nitrogen protection, reacting at 45° C. for 3 h, and then continuing to add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, wherein the mass ratio of the intermediate 1, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1.1:1:1.5, and continuing to react at 60° C. for 4 h. After the reaction is completed, cooling, suction filtering and drying are performed to obtain a phosphorus-containing benzene sulfone chain extender;

[0043] (3) under nitrogen protection, adding polyether polyol and hexamethylene diisocyanate into a reactor, stirring evenly, then adding dibutyltin dilaurate catalyst thereto, reacting at 65° C. for 3 h, then adding phosphorus-containing benzene sulfone chain extender, wherein the mass ratio of polyether polyol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and phosphorus-containing benzene sulfone chain extender is 1.2:1:0.02:0.7, reacting at 55° C. for 1 h, cooling after the reaction, discharging, and obtaining modified polyurethane;

[0044] (4) adding 8 parts by weight of hydroxylated bentonite and 3 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stirring and mixing, reacting at 100° C. for 10 h, and then distilling under reduced pressure, filtering and drying to obtain olefinated bentonite;

[0045] (5) adding olefinic bentonite to N,N-dimethylformamide solvent, stirring evenly, and then adding aqueous hydrogen peroxide solution thereto, wherein the mass ratio of olefinic bentonite to aqueous hydrogen peroxide solution is 1:2.4, reacting at 38° C. for 4 h, and then distilling under reduced pressure, filtering and drying to obtain epoxidized triazine bentonite;

[0046] (6) 70 parts by weight of bentonite, 20 parts by weight of hydroxylated bentonite, 5 parts by weight of modified polyurethane, 12 parts by weight of red mud, 7 parts by weight of biotite, and 7 parts by weight of epoxidized triazine bentonite were added into a reactor and stirred for 30 minutes to form a slurry, which was then added into a mold and reacted at 160° C. for 1 hour. After reaction, the mixture was cooled to obtain a composite material for underground rail transit.

[0047] Example 4

[0048] (1) adding 2,2-bis(bromomethyl)-1,3-propanediol and 2,6-dialdehyde-1,5-dihydroxynaphthalene to an acetone solvent, wherein the mass ratio of 2,2-bis(bromomethyl)-1,3-propanediol to 2,6-dialdehyde-1,5-dihydroxynaphthalene is 1:2.1, stirring evenly, then continuously adding 3 mol / L sodium hydroxide aqueous solution, reacting at 65° C. for 4 h, and after the reaction is completed, neutralizing, concentrating, filtering, washing and drying to obtain an intermediate 1;

[0049] (2) adding the intermediate 1 and 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone to a reactor containing an ethanol solvent, stirring evenly, introducing nitrogen protection, reacting at 40° C. for 2 h, and then continuing to add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, wherein the mass ratio of the intermediate 1, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 0.8:1:1.3, and continuing to react at 50° C. for 3 h. After the reaction is completed, cooling, suction filtering and drying are performed to obtain a phosphorus-containing benzene sulfone chain extender;

[0050] (3) Under nitrogen protection, polyether polyol and hexamethylene diisocyanate are added to a reactor, stirred evenly, and then dibutyltin dilaurate catalyst is added thereto, reacted at 75° C. for 4 hours, and then phosphorus-containing benzene sulfone chain extender is added, wherein the mass ratio of polyether polyol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst, and phosphorus-containing benzene sulfone chain extender is 1.3:1:0.03:0.8, reacted at 65° C. for 2 hours, and after the reaction is completed, cooled and discharged to obtain modified polyurethane;

[0051] (4) adding 10 parts by weight of hydroxylated bentonite and 4 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stirring and mixing, reacting at 115° C. for 12 hours, and then distilling under reduced pressure, filtering and drying to obtain olefinated bentonite;

[0052] (5) adding olefinic bentonite to N,N-dimethylformamide solvent, stirring evenly, and then adding aqueous hydrogen peroxide solution thereto, wherein the mass ratio of olefinic bentonite to aqueous hydrogen peroxide solution is 1:2.4, reacting at 38° C. for 4 h, and then distilling under reduced pressure, filtering and drying to obtain epoxidized triazine bentonite;

[0053] (6) 70 parts by weight of bentonite, 20 parts by weight of hydroxylated bentonite, 5 parts by weight of modified polyurethane, 12 parts by weight of red mud, 7 parts by weight of biotite, and 7 parts by weight of epoxidized triazine bentonite were added into a reactor and stirred for 30 minutes to form a slurry, which was then added into a mold and reacted at 160° C. for 1 hour. After reaction, the mixture was cooled to obtain a composite material for underground rail transit.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 4 is that no modified polyurethane is added.

[0056] Comparative Example 2

[0057] This comparative example is different from Example 4 in that no epoxidized triazine bentonite is added.

[0058] Use an oxygen index meter to test the limiting oxygen index of the material; use a horizontal and vertical combustion instrument to test the combustion level of the material.

[0059] Table 1: Flame retardancy tests.

[0060] project Limiting oxygen index (%) Combustion level Example 1 29.4 V-0 Example 2 31.2 V-0 Example 3 30.1 V-0 Example 4 30.6 V-0 Comparative Example 1 21.7 V-1 Comparative Example 2 20.5 V-1

[0061] It can be seen from Table 1 that the flame retardant effect of Examples 1-4 is better than that of Comparative Examples 1-2, which indicates that the material prepared by the present invention has a good flame retardant effect.

[0062] The mechanical properties of the materials were tested using a universal electronic testing machine with a tensile rate of 100 mm / min.

[0063] Table 2: Tensile strength test.

[0064] project Tensile strength(MPa) Example 1 42.36 Example 2 45.79 Example 3 41.15 Example 4 42..27 Comparative Example 1 24.72 Comparative Example 2 23.49

[0065] It can be seen from Table 2 that the tensile effect of the preparation examples 1-4 of the present invention is better than that of the comparative examples 1-2, and the obtained materials have better tensile strength.

[0066] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A composite material used in underground rail transit, characterized in that: The invention comprises the following components by weight: 60-80 parts by weight of bentonite, 15-25 parts by weight of hydroxylated bentonite, 4-6 parts by weight of modified polyurethane, 10-14 parts by weight of red mud, 6-8 parts by weight of biotite and 4-10 parts by weight of epoxidized triazine bentonite.

2. The composite material for underground rail transit according to claim 1, characterized in that: The preparation method of the phosphorus-modified polyurethane is as follows: (1) Add 2,2-bis(bromomethyl)-1,3-propanediol and 2,6-dialdehyde-1,5-dihydroxynaphthalene to an acetone solvent, stir evenly, then continue to add a 3-5 mol / L sodium hydroxide aqueous solution, react at 65-85° C. for 4-6 hours, and after the reaction is completed, neutralize, concentrate, filter, wash and dry to obtain an intermediate 1; (2) adding the intermediate 1, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone to a reactor containing an ethanol solvent, stirring evenly, introducing nitrogen protection, reacting at 40-65° C. for 2-4 hours, and then continuing to add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and continuing to react at 50-70° C. for 3-5 hours. After the reaction is completed, cooling, suction filtering and drying are performed to obtain a phosphorus-containing benzene sulfone chain extender; (3) Under nitrogen protection, polyether polyol and hexamethylene diisocyanate are added to a reactor and stirred evenly, and then dibutyltin dilaurate catalyst is added thereto, and the reaction is carried out at 60-75° C. for 2-4 hours, and then phosphorus-containing benzene sulfone chain extender is added thereto, and the reaction is carried out at 40-65° C. for 1-2 hours. After the reaction is completed, the reaction is cooled and discharged to obtain a modified polyurethane.

3. The composite material for underground rail transit according to claim 1, characterized in that: The mass ratio of 2,2-bis(bromomethyl)-1,3-propanediol to 2,6-dialdehyde-1,5-dihydroxynaphthalene in (1) is 1:2.1-2.

3.

4. The composite material for underground rail transit according to claim 1, characterized in that: The mass ratio of the intermediate 1, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in (2) is 0.8-1.2:1:1.3-2.

5.

5. The composite material for underground rail transit according to claim 1, characterized in that: The mass ratio of the polyether polyol, hexamethylene diisocyanate, dibutyltin dilaurate catalyst and phosphorus-containing phenylsulfone chain extender in (3) is 1.2-1.3:1:0.01-0.03:0.5-0.

8.

6. The composite material for underground rail transit according to claim 1, characterized in that: The preparation method of the epoxidized triazine bentonite is: S1. Add 5-10 parts by weight of hydroxylated bentonite and 2-4 parts by weight of 2-chloro-4,6-diallyl triazine to N,N-dimethylformamide solvent, stir and mix, react at 95-115°C for 8-12h, and then distill under reduced pressure, filter and dry to obtain olefinated bentonite; S2. Add olefinated bentonite to N,N-dimethylformamide solvent, stir evenly, then add aqueous hydrogen peroxide solution, react at 32-45°C for 4-5h, and then distill under reduced pressure, filter and dry to obtain epoxidized triazine bentonite.

7. The composite material for underground rail transit according to claim 6, characterized in that: The mass ratio of olefinated bentonite to aqueous hydrogen peroxide solution in S2 is 1:2.2-2.

6.

8. A method for preparing a composite material for underground rail transit according to any one of claims 1 to 7, characterized in that: The preparation method of the composite material for underground rail transit comprises the following steps: adding bentonite, hydroxylated bentonite, modified polyurethane, red mud, biotite, and epoxidized triazine bentonite into a reactor, stirring for 20-40 minutes, mixing into slurry, adding the slurry into a mold, reacting at 150-180° C. for 1-2 hours, cooling after reaction, and obtaining the composite material for underground rail transit.

9. A method for preparing a composite material for underground rail transit according to any one of claims 1 to 7, characterized in that: The application of the composite material in underground rail transit is in which a flexible display layer is embedded in the base.