An adaptive expansion type shield tail sealing grease and a preparation method thereof

Abstract

The application discloses a self-adapting expansion type shield tail sealing grease and a preparation method thereof, and relates to the technical field of shield tail sealing grease. The self-adapting expansion type shield tail sealing grease is composed of base oil, expansion agent, thickening and viscosity increasing agent, reinforcing agent, filling agent and modified additive. The expansion agent is composed of carboxymethyl cellulose, modified polyvinyl alcohol and modified sodium polyacrylate according to a mass ratio of 3-5:4-7:4-8. The self-adapting expansion type shield tail sealing grease can contact with underground water and shield tail slurry, and can realize self-expansion. The volume of the expanded shield tail sealing grease is about 1.2-1.5 times of that before expansion. The expanded shield tail sealing grease can fully fill the sealing cavity, increase the pressure of the sealing cavity to resist external grouting pressure and water and soil pressure, make up the pressure loss of the sealing cavity, reduce the pumping frequency and pressure of the shield tail sealing grease, and reduce the grease consumption.

Description

Technical Field

[0001] This invention relates to the field of shield tail sealing grease technology, specifically an adaptive expansion type shield tail sealing grease and its preparation method. Background Technology

[0002] Shield tunneling is a crucial construction method in rail transit development. During shield tunneling, tail sealing is a critical aspect, and its quality directly impacts construction safety. Tail sealing grease, used as the sealing material at the shield tail during tunneling, effectively prevents groundwater and mud from entering the tunnel boring machine (TBM). Current tunnel engineering methods rely solely on continuously injecting grease into the sealing cavity to maintain pressure. However, in shield tunneling, the TBM's tunneling posture adjusts according to project requirements. When the shield's posture changes, the size of the tail sealing cavity also changes. An enlarged sealing cavity leads to rapid pressure loss, resulting in leakage of groundwater and tail slurry. Therefore, developing a sealing grease that can expand adaptively to adapt to the pressure of the sealing cavity is of significant practical importance. Summary of the Invention

[0003] To address the problem in tunnel engineering where maintaining sealing cavity pressure can only be achieved by continuously injecting grease, the present invention aims to provide an adaptive expansion type shield tail sealing grease and its preparation method. The resulting sealing grease can adaptively expand according to changes in the size of the sealing cavity. When groundwater and grout entering the sealing cavity come into contact with the shield tail sealing grease described in this invention, the sealing grease expands rapidly, quickly filling the enlarged sealing cavity, restoring the sealing cavity pressure, and preventing further leakage of liquid.

[0004] To achieve the above objectives, the present invention employs the following technical solution: An adaptive expansion type shield tail sealing grease, by weight, is composed of the following raw materials: 250-380 parts base oil, 110-200 parts expansion agent, 120-250 parts thickener and viscous agent, 10-90 parts reinforcing agent, 250-350 parts filler and 15-30 parts modifying additive. The expanding agent is composed of carboxymethyl cellulose, modified polyvinyl alcohol, and modified sodium polyacrylate in a mass ratio of 3~5:4~7:4~8; The modified polyvinyl alcohol was prepared according to the following steps: Polyvinyl alcohol was dissolved in dimethyl sulfoxide, p-toluenesulfonic acid and stearic acid were added, and the mixture was stirred at 85-90°C for 6-8 hours. The mixture was then cooled to 50-60°C to obtain crude modified polyvinyl alcohol. The obtained crude modified polyvinyl alcohol was added to acetone under stirring, and the precipitate was filtered out. The precipitate was then vacuum dried at 55-65°C for 5-7 hours to obtain modified polyvinyl alcohol. The mass ratio of polyvinyl alcohol, dimethyl sulfoxide, p-toluenesulfonic acid, stearic acid, and acetone is 1:8~10:0.12~0.8:0.15~0.3:10~20; The modified sodium polyacrylate is a cross-linked sodium polyacrylate modified with a silane coupling agent.

[0005] Preferably, the silane coupling agent is hexadecyltrimethoxysilane.

[0006] Preferably, the modified sodium polyacrylate is prepared according to the following steps: The dried cross-linked sodium polyacrylate and anhydrous toluene were mixed and stirred until homogeneous. The mixture was heated to 80-85°C, and hexadecyltrimethoxysilane was added dropwise at a rate of 0.2-0.4 ml / s while stirring. After the addition was complete, the mixture was stirred at a constant temperature for 6-8 hours. The solid product was separated by filtration and then dried under vacuum at 60-70°C for 10-12 hours to obtain modified sodium polyacrylate. The mass ratio of the dried cross-linked sodium polyacrylate, anhydrous toluene, and hexadecyltrimethoxysilane is 1:10~15:0.01~0.03.

[0007] Preferably, the base oil is composed of epoxidized soybean oil and 150N mineral oil in a mass ratio of 3~7:3~7.

[0008] Preferably, the thickening and tackifying agent is composed of polyisobutylene, lithium magnesium silicate, and polymeric rosin in a mass ratio of 6~13:2~5:4~7.

[0009] Preferably, the reinforcing agent is composed of kapok fiber and polypropylene fiber in a mass ratio of 3~30:2~15.

[0010] Preferably, the filler is composed of expanded perlite, calcium carbonate and acrylic bentonite in a mass ratio of 3~5:18~25:3~5.

[0011] Preferably, the modified additive is composed of titanate coupling agent and zinc stearate in a mass ratio of 1~2:1~5.

[0012] Preferably, the 1% aqueous solution of carboxymethyl cellulose has a viscosity of 180~220 mPa·s at 25°C.

[0013] This invention also includes a method for preparing an adaptive expansion type shield tail sealing grease, comprising the following steps: By weight, add 15-30 parts of modified additive and 120-250 parts of thickener to 250-380 parts of base oil, heat to 85-95℃, stir for 20-40 minutes, and cool to 30-40℃ to obtain a mixture; add 110-200 parts of expander to the mixture and stir until homogeneous; then add 10-90 parts of reinforcing agent and 250-350 parts of filler to the mixture and stir until homogeneous to obtain an adaptive expansion shield tail sealing grease.

[0014] Preferably, the stirring speed is 125~300 rpm.

[0015] The present invention has the following advantages over the prior art: The adaptive expansion shield tail sealing grease of the present invention can come into contact with groundwater and shield tail slurry to achieve spontaneous expansion. Its volume after expansion is about 1.3 times that before expansion. The expanded shield tail sealing grease can fully fill the sealing cavity and increase the pressure of the sealing cavity to resist the external grouting pressure and water and soil pressure, make up for the pressure loss of the sealing cavity, reduce the pumping frequency and pressure of the shield tail sealing grease, and reduce the grease consumption.

[0016] The adaptive expansion shield tail sealing grease of the present invention can adapt to changes in the size of the shield tail sealing cavity. When groundwater and slurry enter the sealing cavity, they come into contact with the shield tail sealing grease of the present invention, causing the sealing grease to expand rapidly, quickly fill the enlarged sealing cavity, restore the pressure of the sealing cavity, and prevent further leakage of liquid. Detailed Implementation

[0017] The purpose of this invention is to provide an adaptive expansion type shield tail sealing grease and its preparation method, which is achieved through the following technical solution: In this embodiment of the invention, the carboxymethyl cellulose used has a viscosity of 200 mPa·s in a 1% aqueous solution at 25°C; the degree of alcoholysis of polyvinyl alcohol is 98-100%; the mesh size of sodium polyacrylate is 400 mesh; the molecular weight of polyisobutylene is 2400; the mesh size of lithium magnesium silicate is 325 mesh; the softening point of polymeric rosin is 90°C; the density of the titanate coupling agent is approximately 0.946 g / cm³; the mesh size of zinc stearate is 325 mesh; the fiber length of kapok fiber is 4-8 mm; the fiber length of polypropylene fiber is 6-13 mm; the mesh size of calcium carbonate is 400 mesh; the mesh size of expanded perlite is 325 mesh; and the mesh size of acrylic bentonite is 325 mesh.

[0018] The acrylic bentonite was purchased from BYK Company, model number OPTIGEL CK.

[0019] This invention uses carboxymethyl cellulose, modified polyvinyl alcohol, and modified sodium polyacrylate in a mass ratio of 3~5:4~7:4~8 to obtain an expanding agent. The expanding mechanism is as follows: Carboxymethyl cellulose (CMC), modified polyvinyl alcohol (PVA), and modified sodium polyacrylate (SPA) work synergistically to achieve a rapid response, effective support, and pressure-replenishing adaptive expansion effect. CMC, with its superior hydrophilicity, first rapidly absorbs water; the osmotic pressure generated by the sodium carboxylate groups on its molecular chains actively captures water molecules. The long-chain fiber structure of CMC stretches after absorbing water and intertwines through interchain hydrogen bonds, forming the initial three-dimensional network structure of the entire expansion system. Sodium polyacrylate, modified with hexadecyltrimethoxysilane, is slowly activated within the network established by CMC, absorbing a large amount of water using its own sodium carboxylate groups. Simultaneously, the hydrophobic and oleophilic siloxane limits the unlimited swelling of the SPA chains, preventing the system from collapsing in water; furthermore, it transforms the expansion force of SPA into a continuous stretching of the entire gel network, making the expanded body stronger and more elastic, increasing the pressure in the grease-sealed cavity. The remaining hydrophilic hydroxyl groups on the modified PVA molecular chains further attract water, enhancing the material's expansion capacity. Meanwhile, the modified hydrophobic long alkane chains spontaneously aggregate in water through hydrophobic interactions, forming physical cross-linking points similar to hydrophobic microdomains. These microdomains enhance the mechanical toughness of the gel and constitute a moisture barrier, effectively slowing down moisture diffusion and maintaining the stability of the expanded body.

[0020] The present invention will be further described below with reference to specific embodiments. Example 1

[0021] An adaptive expansion type shield tail sealing grease is composed of the following raw materials: 250 kg base oil, 110 kg expansion agent, 120 kg thickener and viscous agent, 10 kg reinforcing agent, 250 kg filler and 15 kg modified additive. The base oil is composed of epoxidized soybean oil and 150N mineral oil in a mass ratio of 3:7; The thickener is composed of polyisobutylene, lithium magnesium silicate and polymeric rosin in a mass ratio of 6:2:7. The reinforcing agent is composed of kapok fiber and polypropylene fiber in a mass ratio of 3:15; The filler is composed of expanded perlite, calcium carbonate and acrylic bentonite in a mass ratio of 3:18:5. The modified additive is composed of titanate coupling agent and zinc stearate in a mass ratio of 1:5; The expanding agent is composed of carboxymethyl cellulose, modified polyvinyl alcohol, and modified sodium polyacrylate in a mass ratio of 3:4:4; The modified polyvinyl alcohol was prepared according to the following steps: Polyvinyl alcohol was dissolved in dimethyl sulfoxide, p-toluenesulfonic acid and stearic acid were added, and the mixture was stirred at 85°C for 6 hours. The mixture was then cooled to 50°C to obtain crude modified polyvinyl alcohol. The crude modified polyvinyl alcohol was added to acetone under stirring, and the precipitate was filtered out. The precipitate was then vacuum dried at 55°C for 5 hours to obtain modified polyvinyl alcohol. The mass ratio of polyvinyl alcohol, dimethyl sulfoxide, p-toluenesulfonic acid, stearic acid, and acetone is 1:8:0.12:0.15:10. The modified sodium polyacrylate is a silane coupling agent-modified crosslinked sodium polyacrylate, prepared according to the following steps: The dried cross-linked sodium polyacrylate and anhydrous toluene were mixed and stirred until homogeneous. The mixture was heated to 80°C, and hexadecyltrimethoxysilane was added dropwise at a rate of 0.2 ml / s while stirring. After the addition was complete, the mixture was stirred at a constant temperature for 8 hours. The solid product was separated by filtration and then dried under vacuum at 60°C for 10 hours to obtain modified sodium polyacrylate. The mass ratio of the dried cross-linked sodium polyacrylate, anhydrous toluene, and hexadecyltrimethoxysilane was 1:10:0.01. Example 2

[0022] An adaptive expansion type shield tail sealing grease is composed of the following raw materials: 380 kg base oil, 200 kg expansion agent, 250 kg thickener and viscous agent, 90 kg reinforcing agent, 350 kg filler and 30 kg modified additive. The base oil is composed of epoxidized soybean oil and 150N mineral oil in a mass ratio of 7:3; The thickener is composed of polyisobutylene, lithium magnesium silicate and polymeric rosin in a mass ratio of 13:5:4. The reinforcing agent is composed of kapok fiber and polypropylene fiber in a mass ratio of 15:1; The filler is composed of expanded perlite, calcium carbonate and acrylic bentonite in a mass ratio of 5:25:3. The modified additive is composed of titanate coupling agent and zinc stearate in a mass ratio of 2:1; The expanding agent is composed of carboxymethyl cellulose, modified polyvinyl alcohol, and modified sodium polyacrylate in a mass ratio of 5:7:8; The modified polyvinyl alcohol was prepared according to the following steps: Polyvinyl alcohol was dissolved in dimethyl sulfoxide, p-toluenesulfonic acid and stearic acid were added, and the mixture was stirred at 90°C for 8 hours. The mixture was then cooled to 60°C to obtain crude modified polyvinyl alcohol. The crude modified polyvinyl alcohol was added to acetone under stirring, and the precipitate was filtered out. The precipitate was then vacuum dried at 65°C for 7 hours to obtain modified polyvinyl alcohol. The mass ratio of polyvinyl alcohol, dimethyl sulfoxide, p-toluenesulfonic acid, stearic acid, and acetone is 1:10:0.8:0.3:20. The modified sodium polyacrylate is a silane coupling agent-modified crosslinked sodium polyacrylate, prepared according to the following steps: The dried cross-linked sodium polyacrylate and anhydrous toluene were mixed and stirred until homogeneous. The mixture was heated to 85°C, and hexadecyltrimethoxysilane was added dropwise at a rate of 0.4 ml / s while stirring. After the addition was complete, the mixture was stirred at a constant temperature for 6 hours. The solid product was separated by filtration and then dried under vacuum at 70°C for 10 hours to obtain modified sodium polyacrylate. The mass ratio of the dried cross-linked sodium polyacrylate, anhydrous toluene, and hexadecyltrimethoxysilane was 1:15:0.03. Example 3

[0023] An adaptive expansion shield tail sealing grease is composed of the following raw materials: 300 kg base oil, 140 kg expansion agent, 220 kg thickener and viscous agent, 80 kg reinforcing agent, 280 kg filler and 16 kg modified additive. The base oil is composed of epoxidized soybean oil and 150N mineral oil in a mass ratio of 4:6; The thickener is composed of polyisobutylene, lithium magnesium silicate and polymeric rosin in a mass ratio of 7:3:5. The reinforcing agent is composed of kapok fiber and polypropylene fiber in a mass ratio of 5:8; The filler is composed of expanded perlite, calcium carbonate and acrylic bentonite in a mass ratio of 1:5:1; The modified additive is composed of titanate coupling agent and zinc stearate in a mass ratio of 3:4; The expanding agent is composed of carboxymethyl cellulose, modified polyvinyl alcohol, and modified sodium polyacrylate in a mass ratio of 4:5:7; The modified polyvinyl alcohol was prepared according to the following steps: Polyvinyl alcohol was dissolved in dimethyl sulfoxide, p-toluenesulfonic acid and stearic acid were added, and the mixture was stirred at 86°C for 7 hours. The mixture was then cooled to 52°C to obtain crude modified polyvinyl alcohol. The crude modified polyvinyl alcohol was added to acetone under stirring, and the precipitate was filtered out. The precipitate was then vacuum dried at 56°C for 5.5 hours to obtain modified polyvinyl alcohol. The mass ratio of polyvinyl alcohol, dimethyl sulfoxide, p-toluenesulfonic acid, stearic acid, and acetone is 1:8.5:0.3:0.2:12. The modified sodium polyacrylate is a silane coupling agent-modified crosslinked sodium polyacrylate, prepared according to the following steps: The dried cross-linked sodium polyacrylate and anhydrous toluene were mixed and stirred until homogeneous. The mixture was heated to 82°C, and hexadecyltrimethoxysilane was added dropwise at a rate of 0.25 ml / s while stirring. After the addition was complete, the mixture was stirred at a constant temperature for 6.5 hours. The solid product was separated by filtration and then vacuum dried at 62°C for 10.5 hours to obtain modified sodium polyacrylate. The mass ratio of the dried cross-linked sodium polyacrylate, anhydrous toluene, and hexadecyltrimethoxysilane was 1:12:0.02. Example 4

[0024] An adaptive expansion type shield tail sealing grease is composed of the following raw materials: 320 kg base oil, 180 kg expansion agent, 150 kg thickener and viscous agent, 20 kg reinforcing agent, 320 kg filler and 28 kg modified additive. The base oil is composed of epoxidized soybean oil and 150N mineral oil in a mass ratio of 5:6; The thickener is composed of polyisobutylene, lithium magnesium silicate and polymeric rosin in a mass ratio of 8:3:5; The reinforcing agent is composed of kapok fiber and polypropylene fiber in a mass ratio of 20:7; The filler is composed of expanded perlite, calcium carbonate and acrylic bentonite in a mass ratio of 4:22:3; The modified additive is composed of titanate coupling agent and zinc stearate in a mass ratio of 8:15; The expanding agent is composed of carboxymethyl cellulose, modified polyvinyl alcohol, and modified sodium polyacrylate in a mass ratio of 4:6:5; The modified polyvinyl alcohol was prepared according to the following steps: Polyvinyl alcohol was dissolved in dimethyl sulfoxide, p-toluenesulfonic acid and stearic acid were added, and the mixture was stirred at 88°C for 7.5 hours. The mixture was then cooled to 58°C to obtain crude modified polyvinyl alcohol. The crude modified polyvinyl alcohol was added to acetone under stirring, and the precipitate was filtered out. The precipitate was then vacuum dried at 62°C for 6.5 hours to obtain modified polyvinyl alcohol. The mass ratio of polyvinyl alcohol, dimethyl sulfoxide, p-toluenesulfonic acid, stearic acid, and acetone is 1:9.5:0.5:0.18:18. The modified sodium polyacrylate is a silane coupling agent-modified crosslinked sodium polyacrylate, prepared according to the following steps: The dried cross-linked sodium polyacrylate and anhydrous toluene were mixed and stirred until homogeneous. The mixture was heated to 84°C, and hexadecyltrimethoxysilane was added dropwise at a rate of 0.35 ml / s while stirring. After the addition was complete, the mixture was stirred at a constant temperature for 7.5 hours. The solid product was separated by filtration and then dried under vacuum at 68°C for 11.5 hours to obtain modified sodium polyacrylate. The mass ratio of the dried cross-linked sodium polyacrylate, anhydrous toluene, and hexadecyltrimethoxysilane was 1:14:0.025. Example 5

[0025] An adaptive expansion shield tail sealing grease is composed of the following raw materials: 300 kg base oil, 150 kg expansion agent, 200 kg thickener and viscous agent, 50 kg reinforcing agent, 300 kg filler and 20 kg modifier. The base oil is composed of epoxidized soybean oil and 150N mineral oil in a mass ratio of 4:5; The thickener is composed of polyisobutylene, lithium magnesium silicate and polymeric rosin in a mass ratio of 12:4:5; The reinforcing agent is composed of kapok fiber and polypropylene fiber in a mass ratio of 25:7; The filler is composed of expanded perlite, calcium carbonate and acrylic bentonite in a mass ratio of 1:5:1; The modified additive is composed of titanate coupling agent and zinc stearate in a mass ratio of 3:8; The expanding agent is composed of carboxymethyl cellulose, modified polyvinyl alcohol, and modified sodium polyacrylate in a mass ratio of 4:5:6; The modified polyvinyl alcohol was prepared according to the following steps: Polyvinyl alcohol was dissolved in dimethyl sulfoxide, p-toluenesulfonic acid and stearic acid were added, and the mixture was stirred at 88°C for 7 hours. The mixture was then cooled to 55°C to obtain crude modified polyvinyl alcohol. The crude modified polyvinyl alcohol was added to acetone under stirring, and the precipitate was filtered out. The precipitate was then vacuum dried at 60°C for 6 hours to obtain modified polyvinyl alcohol. The mass ratio of polyvinyl alcohol, dimethyl sulfoxide, p-toluenesulfonic acid, stearic acid, and acetone is 1:9:0.5:0.2:15. The modified sodium polyacrylate is a silane coupling agent-modified crosslinked sodium polyacrylate, prepared according to the following steps: The dried cross-linked sodium polyacrylate and anhydrous toluene were mixed and stirred until homogeneous. The mixture was heated to 84°C, and hexadecyltrimethoxysilane was added dropwise at a rate of 0.3 ml / s while stirring. After the addition was complete, the mixture was stirred at a constant temperature for 7 hours. The solid product was separated by filtration and then dried under vacuum at 65°C for 11 hours to obtain modified sodium polyacrylate. The mass ratio of the dried cross-linked sodium polyacrylate, anhydrous toluene, and hexadecyltrimethoxysilane was 1:12:0.02. Example 6

[0026] The preparation method of the adaptive expansion type shield tail sealing grease described in Example 1 includes the following steps: Add 15 kg of modified additive and 120 kg of thickener to 250 kg of base oil, heat to 85°C, stir at 125 rpm for 40 minutes, and cool to 30°C to obtain a mixture; add 110 kg of expander to the mixture, stir at 125 rpm until well mixed, then add 10 kg of reinforcing agent and 250 kg of filler to the mixture, stir at 125 rpm until well mixed to obtain an adaptive expansion shield tail sealing grease. Example 7

[0027] The preparation method of the adaptive expansion type shield tail sealing grease described in Example 2 includes the following steps: Add 30 kg of modified additive and 250 kg of thickener to 380 kg of base oil, heat to 95°C, stir at 300 rpm for 20 minutes, and cool to 40°C to obtain a mixture; add 200 kg of expander to the mixture, stir at 300 rpm to mix evenly, then add 90 kg of reinforcing agent and 350 kg of filler to the mixture, stir at 300 rpm to mix evenly, to obtain an adaptive expansion shield tail sealing grease. Example 8

[0028] The preparation method of the adaptive expansion type shield tail sealing grease described in Example 3 includes the following steps: Add 16 kg of modified additive and 220 kg of thickener to 300 kg of base oil, heat to 90°C, stir at 200 rpm for 25 minutes, and cool to 32°C to obtain a mixture; add 140 kg of expander to the mixture, stir at 150 rpm to mix evenly, then add 80 kg of reinforcing agent and 280 kg of filler in sequence, stir at 180 rpm to mix evenly, to obtain an adaptive expansion shield tail sealing grease. Example 9

[0029] The preparation method of the adaptive expansion type shield tail sealing grease described in Example 4 includes the following steps: Add 28 kg of modified additive and 150 kg of thickener to 320 kg of base oil, heat to 88°C, stir at 150 rpm for 35 minutes, and cool to 36°C to obtain a mixture; add 180 kg of expander to the mixture, stir at 220 rpm to mix evenly, then add 20 kg of reinforcing agent and 320 kg of filler in sequence, stir at 250 rpm to mix evenly, to obtain an adaptive expansion shield tail sealing grease. Example 10

[0030] The preparation method of the adaptive expansion type shield tail sealing grease described in Example 5 includes the following steps: Add 20 kg of modified additive and 200 kg of thickener to 300 kg of base oil, heat to 90°C, stir at 200 rpm for 30 minutes, and cool to 35°C to obtain a mixture; add 150 kg of expander to the mixture, stir at 200 rpm until well mixed, then add 50 kg of reinforcing agent and 300 kg of filler to the mixture, stir at 200 rpm until well mixed to obtain an adaptive expansion shield tail sealing grease.

[0031] The performance of the adaptive expansion-type shield tail sealing greases obtained in Examples 6-10 was tested. Pumpability, water pressure resistance, and cone penetration were tested according to T / CC 8-2023. The expansion rate was tested as follows: a certain mass of shield tail sealing grease sample was taken and added to an expansion rate measuring tube, compacted, and the volume before expansion was read. Then, twice the sample mass of water was added, and the mixture was allowed to stand for 1 hour. The volume after expansion was read. The expansion rate was calculated as (volume after expansion - volume before expansion) / volume before expansion. The results are shown in Table 1.

[0032] Table 1. Performance test results of adaptive expansion shield tail sealing grease obtained in Examples 6-10 Example 6 36.1 18.5 6.5 218.7 Example 7 19.8 35.1 7.7 204.5 Example 8 27.1 28.5 7.5 209.7 Example 9 30.2 25.2 7.0 212.2 Example 10 28.4 37.4 7.0 205.1 As can be seen from the results in Table 1, the adaptive expansion shield tail sealing grease of the present invention has good pumpability, water pressure resistance and sealing performance and cone penetration. It can also come into contact with groundwater and shield tail slurry to achieve spontaneous expansion. Its volume after expansion is about 1.3 times that before expansion.

Claims

1. An adaptive expansion type shield tail sealing grease, characterized in that: By weight, it is composed of the following raw materials: 250-380 parts base oil, 110-200 parts expander, 120-250 parts thickener and viscous agent, 10-90 parts reinforcing agent, 250-350 parts filler and 15-30 parts modifying additive. The expanding agent is composed of carboxymethyl cellulose, modified polyvinyl alcohol, and modified sodium polyacrylate in a mass ratio of 3~5:4~7:4~8; The modified polyvinyl alcohol was prepared according to the following steps: Polyvinyl alcohol was dissolved in dimethyl sulfoxide, p-toluenesulfonic acid and stearic acid were added, and the mixture was stirred at 85-90°C for 6-8 hours. The mixture was then cooled to 50-60°C to obtain crude modified polyvinyl alcohol. The obtained crude modified polyvinyl alcohol was added to acetone under stirring, and the precipitate was filtered out. The precipitate was then vacuum dried at 55-65°C for 5-7 hours to obtain modified polyvinyl alcohol. The mass ratio of polyvinyl alcohol, dimethyl sulfoxide, p-toluenesulfonic acid, stearic acid, and acetone is 1:8~10:0.12~0.8:0.15~0.3:10~20; The modified sodium polyacrylate is a cross-linked sodium polyacrylate modified with a silane coupling agent; The base oil is composed of epoxidized soybean oil and 150N mineral oil in a mass ratio of 3~7:3~7; the thickener is composed of polyisobutylene, lithium magnesium silicate and polymerized rosin in a mass ratio of 6~13:2~5:4~7. The reinforcing agent is composed of kapok fiber and polypropylene fiber in a mass ratio of 3~30:2~15; The filler is composed of expanded perlite, calcium carbonate and acrylic bentonite in a mass ratio of 3~5:18~25:3~5; The modified additive is composed of titanate coupling agent and zinc stearate in a mass ratio of 1~2:1~5.

2. The adaptive expansion shield tail sealing grease according to claim 1, characterized in that: The silane coupling agent is hexadecyltrimethoxysilane.

3. The adaptive expansion shield tail sealing grease according to claim 1, characterized in that: The modified sodium polyacrylate is prepared according to the following steps: The dried cross-linked sodium polyacrylate and anhydrous toluene were mixed and stirred until homogeneous. The mixture was heated to 80-85°C, and hexadecyltrimethoxysilane was added dropwise at a rate of 0.2-0.4 ml / s while stirring. After the addition was complete, the mixture was stirred at a constant temperature for 6-8 hours. The solid product was separated by filtration and then dried under vacuum at 60-70°C for 10-12 hours to obtain modified sodium polyacrylate. The mass ratio of the dried cross-linked sodium polyacrylate, anhydrous toluene, and hexadecyltrimethoxysilane is 1:10~15:0.01~0.

03.

4. The method for preparing an adaptive expansion type shield tail sealing grease according to claim 1, characterized in that: Includes the following steps: By weight, add 15-30 parts of modified additive and 120-250 parts of thickener to 250-380 parts of base oil, heat to 85-95℃, stir for 20-40 minutes, and cool to 30-40℃ to obtain a mixture; add 110-200 parts of expander to the mixture and stir until homogeneous; then add 10-90 parts of reinforcing agent and 250-350 parts of filler to the mixture and stir until homogeneous to obtain an adaptive expansion shield tail sealing grease.

5. The method for preparing an adaptive expansion type shield tail sealing grease according to claim 4, characterized in that: The stirring speed should be 125~300 rpm when mixing.