Low-temperature-resistant stable shield tail sealing grease and preparation method thereof

Abstract

The embodiment of the invention discloses low-temperature-resistant stable shield tail sealing grease and a preparation method thereof. The low-temperature-resistant stable shield tail sealing grease is prepared from the following components in parts by weight: 3.6 to 4.6 parts of dispersing type fiber, 9.7 to 10.5 parts of viscosity modifier, 0 to 25.5 parts of consistency modifier, 0 to 17.4 parts of viscosity index improver, 6.8 to 9.8 parts of lubricant, 42.7 to 46.4 parts of filler, 4.9 to 15.5 parts of water-resistant reinforcing filler and 0 to 2.8 parts of thermal resistance filler. The shield tail sealing grease provided by the invention has good consistency, flowability, pumpability, adhesivity and water-pressure-resistant sealing performance under the conditions of room temperature and low temperature, meets the performance requirements of the shield tail sealing grease, can ensure safe and smooth shield construction, has the production cost greatly lower than the market price on the premise of reaching the same performance index, and has wide application prospects. Wide market popularization and application prospects are realized.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of functional grease, and in particular to a low-temperature resistant and stable shield tail sealing grease and a preparation method thereof. Background Art

[0002] Shield tail sealing grease is the main material for shield tail sealing and waterproofing in shield construction. During the underground excavation of the shield machine, the shield tail sealing grease plays a key role in preventing groundwater, soil and other substances from entering the shield machine.

[0003] At present, most sealing grease products on the market can achieve practical use effects when sealed and stored at room temperature, but they are prone to hardening and reduced fluidity in low-temperature environments. Therefore, it is necessary to develop a low-temperature resistant and stable grease product that can effectively avoid the above situation and ensure good pumpability and sealing performance.

[0004] Chinese patent CN116042300A discloses a low temperature resistant shield tail sealing grease and a preparation method thereof, wherein the raw material composition comprises base oil, plasticizer, pour point depressant, auxiliary agent, lubricant, thickener, olive extract, chitosan, sweet potato leaf stem extract, blueberry extract, talcum, cobalt oxide and foaming agent. The pour point depressant of base oil is regulated by pour point depressant to obtain a grease product with low temperature resistance. The process is multi-component and the process is complicated, and the material cost of using pour point depressant, plasticizer such as dioctyl phthalate is higher in addition. Chinese patent CN111394160A discloses a high performance shield tail sealing grease and a preparation method thereof, wherein the mineral fiber is used as a sealant, calcium carbonate is used as a filler and an anti-wear agent in the components, and although the production cost is significantly reduced under the condition of ensuring sealing and pumpability, it does not possess good low temperature resistance. Summary of the invention

[0005] To this end, the embodiment of the present invention provides a low-temperature resistant and stable shield tail sealing grease and a preparation method thereof. The present invention solves the problems of poor low-temperature resistance and high production cost of most of the currently disclosed products. On the premise of achieving the same performance indicators, the production cost is much lower than the market price, and has broad market promotion and application prospects.

[0006] In order to achieve the above purpose, the embodiment of the present invention provides the following technical solutions:

[0007] According to a first aspect of an embodiment of the present invention, the present invention provides a low-temperature resistant and stable shield tail sealing grease, which comprises, by weight:

[0008] Dispersed fiber 3.6-4.6 parts, viscosity regulator 9.7-10.5 parts, consistency regulator 0-25.5 parts, viscosity index improver 0-17.4 parts, lubricant 6.8-9.8 parts, filler 42.7-46.4 parts, water resistance enhancing filler 4.9-15.5 parts, thermal resistance filler 0-2.8 parts.

[0009] Furthermore, the dispersed fibers are selected from one or both of wood fibers and polypropylene fibers.

[0010] Furthermore, the viscosity modifier is selected from one or more of C5 petroleum resin, C9 petroleum resin, and 150N mineral oil.

[0011] Furthermore, the consistency regulator is selected from one or both of low-viscosity polyisobutylene and medium-viscosity polyisobutylene.

[0012] Furthermore, the viscosity index improver is an ethylene-propylene copolymer.

[0013] Furthermore, the lubricant is selected from butter.

[0014] Furthermore, the filler is selected from one or both of heavy activated calcium carbonate powder and light activated calcium carbonate powder.

[0015] Furthermore, the water resistance enhancing filler is sodium bentonite.

[0016] Furthermore, the thermal resistance filler is mica sheet.

[0017] According to a second aspect of an embodiment of the present invention, the present invention provides a method for preparing the low-temperature resistant and stable shield tail sealing grease as described in any one of the above items, the method comprising the following steps:

[0018] (1) Add the dispersed fibers and the viscosity modifier into a kneader, control the inner wall temperature of the kneader to 80±5°C, and knead at a speed of 70±10 rpm until the dispersed fibers are in the form of fragments, more than 90% of the dispersed fibers are soaked in the viscosity modifier, and there is no obvious residual viscosity modifier at the bottom of the kneader;

[0019] (2) Add consistency regulator, viscosity index improver and lubricant to the kneader, maintain the inner wall temperature of the kneader at 80±5°C, adjust the kneader speed to 80±20 rpm, knead for at least 40 min, and ensure that the surface color of the mixture is uniform and there is no obvious stratification. Randomly sample the product from the upper, middle and lower parts of the kneader. When the measured temperature reaches above 75°C, proceed to the next step. Otherwise, continue to increase the kneading time to meet this requirement.

[0020] (3) Add water-resistant fillers and heat-resistant fillers to the kneader, maintain the inner wall temperature of the kneader at 80±5°C, adjust the kneader speed to 100±10 rpm, knead for at least 60 min, and ensure that the surface color of the mixture is uniform and there is no obvious stratification. Randomly sample the product from the upper, middle and lower parts of the kneader. When the measured temperature reaches above 75°C, proceed to the next step. Otherwise, continue to increase the kneading time to meet this requirement.

[0021] (4) Add filler to the kneader, maintain the inner wall temperature of the kneader at 80±5°C, adjust the kneader speed to 120±10 rpm, and knead for at least 60 min. Divide the filler into 3 equal parts by total mass and add them in 3 times, with an interval of 10 to 15 minutes each time, until the mixture is beige in color and has no obvious stratification. Randomly sample the product from the upper, middle and lower parts of the kneader. When the measured temperature reaches above 75°C and there is no block with a diameter greater than 5 cm, proceed to the next step. Otherwise, continue to increase the kneading time to meet this requirement.

[0022] (5) After naturally cooling to room temperature, the mixture is sealed and stored to obtain the low-temperature resistant and stable shield tail sealing grease.

[0023] The embodiments of the present invention have the following advantages:

[0024] The shield tail sealing grease provided by the present invention has good consistency, fluidity, pumpability, adhesion and water pressure resistance and sealing performance at room temperature and low temperature conditions, meets the performance requirements of the shield tail sealing grease, can ensure the safety and smooth progress of shield construction, and on the premise of achieving the same performance indicators, the production cost is much lower than the market price, and has broad market promotion and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0026] Figure 1 A flow chart for preparing the low-temperature resistant and stable shield tail sealing grease provided by the present invention;

[0027] Figure 2 A schematic diagram of the state before the adhesion experiment provided by the present invention;

[0028] Figure 3 A schematic diagram of the state after the adhesion experiment provided by the present invention;

[0029] Figure 4 Schematic diagram of the pumping rate test device provided by the present invention, wherein: 1-air compressor, 2-high-pressure air pipe, 3-pressure regulating valve, 4-solenoid valve, 5-three-way quick connector, 6-check valve, 7-conductor, 8-DC power supply, 9-charging syringe, 10-piston;

[0030] 5 is a curve showing the performance variation of the low temperature resistant and stable shield tail sealing grease with temperature provided in Example 1 of the present invention, wherein a is the cone penetration, b is the flow / pumping rate, c is the adhesion rate, and d is the filtration loss. DETAILED DESCRIPTION

[0031] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The invention provides a low-temperature resistant and stable shield tail sealing grease. The raw materials thereof include, by weight, 3.6-4.6 parts of dispersed fibers, 9.7-10.5 parts of viscosity regulators, 0-25.5 parts of consistency regulators, 0-17.4 parts of viscosity index improvers, 6.8-9.8 parts of lubricants, 42.7-46.4 parts of fillers, 4.9-15.5 parts of water resistance enhancing fillers, and 0-2.8 parts of thermal resistance fillers.

[0033] Among them, the dispersed fibers are used to increase the strength and toughness of the shield tail sealing grease, thereby maintaining the sealing performance. Preferably, the dispersed fibers are selected from one or two of wood fibers and polypropylene fibers. In some preferred embodiments, the dispersed fibers are composed of wood fibers and polypropylene fibers, with a diameter of 5-20 μm and a length of 0.8±0.2 mm and 3.0±1.0 mm. Research and development found that the use of fiber materials of different lengths and materials is conducive to forming a denser mesh structure inside the grease, thereby enhancing the water pressure resistance and sealing performance. At the same time, the combined use of wood fibers and polypropylene fibers is more conducive to maintaining the fluidity and pumpability of the shield tail sealing grease in a low temperature environment than a single component.

[0034] The viscosity regulator is used to adjust the viscosity of the tail seal grease. Preferably, the viscosity regulator is selected from one or more of C5 petroleum resin, C9 petroleum resin, and 150N mineral oil. In some specific embodiments, the viscosity regulator is composed of C5 petroleum resin, C9 petroleum resin, and 150N mineral oil in a mass ratio of 1:1.5 - 1.8:3.8 - 4. Its preparation method is: C5 petroleum resin, C9 petroleum resin, and 150N mineral oil are fused at a temperature of 120°C - 130°C. The viscosity regulator prepared by the above method is a viscous liquid. Using the above viscosity regulator can effectively balance the fluidity and sealing performance of the tail seal grease in high-temperature and low-temperature environments.

[0035] The consistency regulator is used to adjust the consistency of the tail seal grease, and can maintain a relatively stable consistency within different temperature ranges, so that the tail seal grease can effectively play a sealing role. Preferably, the consistency regulator is selected from one or both of low-viscosity polyisobutylene and medium-viscosity polyisobutylene. In some specific embodiments, the apparent viscosity of the low-viscosity polyisobutylene at 100°C is 600 - 650 mm 2 / s, and the apparent viscosity of the medium-viscosity polyisobutylene at 100°C is 4000 - 5000 mm 2 / s.

[0036] The viscosity index improver is used to improve the viscosity-temperature performance of the tail seal grease, so that the grease can maintain a relatively stable viscosity at different temperatures, which is beneficial to improving the fluidity of the grease at low temperatures and the sealing performance at high temperatures. Preferably, the viscosity index improver is an ethylene-propylene copolymer. In some specific embodiments, the kinematic viscosity of the ethylene-propylene copolymer at 100°C is 400 - 800 mm 2 / s.

[0037] The lubricant is used to reduce the friction between the tail shield and the segment, and improve the sealing performance and pumpability of the tail seal grease. Preferably, the lubricant is butter.

[0038] The filler plays a "skeleton" role in the tail grease system. On the one hand, it ensures that the tail grease material has appropriate plasticity and strength. On the other hand, it fills the volume of the grease and reduces the production cost of the grease. Preferably, the filler is selected from one or both of heavy calcium carbonate powder and light calcium carbonate powder. More preferably, the filler is composed of heavy calcium carbonate powder and light calcium carbonate powder in a mass ratio of 2.2 - 3.6:1. It is found that using the above filler is beneficial to improving the sealing performance of the grease at low temperatures.

[0039] The water-resistant filler is used to enhance the water resistance of the shield tail sealing grease. Preferably, the water-resistant filler is sodium bentonite. Sodium bentonite has water-absorbing and swelling properties, and can form a dense mud film on the surface / inside of the grease under the action of external water pressure, which helps to improve the water pressure sealing performance of the shield tail sealing grease. At the same time, the solubility is less affected by temperature changes, and other properties are almost unchanged.

[0040] The heat resistance filler is used to maintain the shield tail sealing grease in a relatively stable temperature state. Preferably, the heat resistance filler is a mica sheet.

[0041] Example 1

[0042] The present embodiment provides a low-temperature resistant and stable shield tail sealing grease, whose raw materials are: 1.9 parts of wood fiber (length 0.8±0.2mm), 2.3 parts of polypropylene fiber (length 3.0±1.0mm), 1.5 parts of C5 petroleum resin, 2.4 parts of C9 petroleum resin, 5.8 parts of 150N mineral oil, 0 parts of low-viscosity polyisobutylene, 0 parts of medium-viscosity polyisobutylene, 7.7 parts of ethylene-propylene copolymer T613, 9.7 parts of ethylene-propylene copolymer T614, 6.8 parts of butter, 36.2 parts of heavy activated calcium carbonate powder, 10.2 parts of light activated calcium carbonate powder, 15.5 parts of sodium bentonite, and 0 parts of mica flakes.

[0043] The preparation method of the above-mentioned low temperature resistant stable shield tail sealing grease comprises the following steps (see the flow chart) Figure 1 ):

[0044] (1) Add C5 petroleum resin, C9 petroleum resin and 150N mineral oil into a reaction kettle, stir at 125°C and 30 rpm for more than 30 minutes, and keep warm at 110°C. If there is no obvious stratification of the mixture within 30 minutes, the viscosity regulator is prepared.

[0045] (2) Add wood fiber, polypropylene fiber and the viscosity regulator prepared in step (1) into a kneader, control the temperature of the kneader at 80±5°C, knead at 70±10 rpm, and ensure that the stirring time is more than 40 minutes, until the dispersed fibers are in the form of fragments, more than 90% of the dispersed fibers are soaked in the viscosity regulator, and there is no obvious residual viscosity regulator at the bottom of the kneader, thereby obtaining a basic mixture A.

[0046] (3) On the basis of basic mixture A, low-viscosity polyisobutylene, medium-viscosity polyisobutylene, ethylene-propylene copolymer T613, ethylene-propylene copolymer T614 and butter are added into the kneader in sequence, the inner wall temperature of the kneader is maintained at 80±5°C, the kneading speed is adjusted to 80±20 rpm, the kneading time is 1 h, and the surface color of the mixture is uniform without obvious stratification. The products are randomly sampled from the upper, middle and lower parts of the kneader, and the actual sample temperature reaches above 75°C to obtain intermediate product B.

[0047] (4) Sodium bentonite and mica flakes were added to the intermediate product B, the inner wall temperature of the kneader was maintained at 80±5°C, the kneader speed was adjusted to 100±10 rpm, the kneading time was at least 60 min, and the surface color of the mixture was uniform without obvious stratification. The products were randomly sampled from the upper, middle and lower parts of the kneader, and the sample temperature was tested to be above 75°C to obtain the intermediate product C.

[0048] (5) Add heavy activated calcium carbonate powder and light activated calcium carbonate powder (premixed or added separately) to the intermediate product C, and divide them into 3 equal parts by total mass. Add them in 3 times, with an interval of 10 minutes between each addition. Maintain the inner wall temperature of the kneader at 80±5℃, adjust the kneader speed to 120±10 rpm, and knead for at least 60 minutes until the mixture is beige in color and has no obvious stratification. Randomly sample the product from the upper, middle and lower parts of the kneader. The sample temperature is above 75℃, and there is no block with a diameter greater than 5 cm in the sample.

[0049] (6) After naturally cooling to room temperature, seal and store to obtain low-temperature resistant and stable shield tail sealing grease.

[0050] Example 2-3

[0051] The preparation method of Example 2-3 is the same as that of Example 1, except that the raw materials and the amounts used are different.

[0052] The raw materials and amounts of Examples 1-3 are shown in Table 1 below.

[0053] Table 1

[0054]

[0055] Comparative Example 1

[0056] This comparative example provides a low temperature resistant and stable shield tail sealing grease, which is different from Example 1 only in that the viscosity modifier used is composed of 1.5 parts of hexadecyl dimethyl tertiary amine, 2.4 parts of oleic acid amide and 5.8 parts of castor oil polyoxyethylene ether. Other materials and production processes remain unchanged.

[0057] Comparative Example 2

[0058] This comparative example provides a low temperature resistant and stable shield tail sealing grease, which is different from Example 2 only in that the consistency regulator used in this comparative example is composed of 9.4 parts of ethylene glycol and 16.1 parts of stearic acid composite titanium soap. Other materials and production processes remain unchanged.

[0059] Comparative Example 3

[0060] This comparative example provides a low temperature resistant and stable shield tail sealing grease, which is different from Example 3 only in that an equal amount of 150BS base oil is used to replace butter, and other materials and production processes remain unchanged.

[0061] Test Example 1

[0062] Performance Testing

[0063] (1) Cone penetration

[0064] GBT269-1991- Determination of cone penetration of lubricating grease and petroleum grease.

[0065] (2) Flow rate

[0066] GB / T 3682-2000-Determination of mass flow rate and volume flow rate of thermoplastic melts.

[0067] (3) Water pressure resistance

[0068] "T / CPCIF0042.1-2020-Shield Sealing Grease Series Products and Test Methods", Matsumura sealing test method. The smaller the filtration loss, the better the water pressure resistance and sealing performance.

[0069] (4) Density

[0070] GB4472-84- General rules for determination of density and relative density of chemical products.

[0071] (5) Adhesion rate

[0072] The good adhesion of the shield tail grease is an important factor in ensuring the grease sealing performance and reducing material consumption. At present, there is no unified standard for testing the adhesion of the shield tail grease. The present invention uses a self-developed device to test the adhesion.

[0073] See also Figure 2-3 The device includes a fixed plate (an acrylic plate with a length of 300 mm, a width of 100 mm, and a thickness of 3 mm), a sliding plate (an acrylic plate with a length of 100 mm, a width of 100 mm, and a thickness of 3 mm), a traction device (an 80-screw linear module, not shown), and a stepper motor (not shown), wherein the traction device can enable the sliding plate to maintain a uniform motion at any speed between 1 and 50 mm / s.

[0074] Specifically, the device uses the adhesion rate N to test the adhesion results. j To characterize, N j The larger it is, the larger the adhesion area of ​​the grease on the fixed plate through traction, the more uniform the grease adhesion is, and the better the adhesion of the grease.

[0075]

[0076] Where: N j — Grease adhesion rate;

[0077] m 1 —Total mass of grease adhering to the fixing plate;

[0078] m 2 —Total mass of grease remaining on the sliding plate.

[0079] (6) Pumping rate

[0080] Pumpability is a common indicator for measuring the pumpability of shield tail sealing grease under specific temperature and pressure. At present, there is no unified standard for the testing method and equipment for the pumpability of shield tail grease. The present invention uses an independently developed device to test the pumping rate of shield tail sealing grease under specific temperature and pressure, and reflects the pumpability of the sealing grease by comparing the size of the pumping rate.

[0081] Specifically, the developed pumping performance test device is mainly composed of an air compressor 1, a high-pressure air pipe 2, a pressure regulating valve 3, a solenoid valve 4, a three-way quick connector 5, a check valve 6, a wire 7, a DC power supply 8, a charging syringe 9, and a piston 10 (see Figure 4 ).

[0082] More specifically, the charging syringe 9 is a cylindrical container with an inner diameter of 49.5 mm and a height of 268 mm. The basic steps of the test are as follows: at room temperature of 25±1°C, the grease to be tested is filled in the charging syringe 9, with a filling height of 200 mm. Under the action of an air pressure of 0.2 MPa, the piston 10 moves downward, and the grease to be tested is extruded through the discharge port (inner diameter 11.3 mm) at the bottom of the charging syringe 9, and the mass m of the extruded grease and the test time t are recorded. The extrusion rate of the grease to be tested under a certain pressure is calculated according to the following formula, which is the pumping rate v of the grease.

[0083] v = m / t

[0084] Where: v—pumping rate, g / min;

[0085] m—oil mass, g;

[0086] t—Pumping time, min.

[0087] The performance requirements of shield tail sealing grease are shown in Table 2 below.

[0088] Table 2

[0089]

[0090] The performance test results of Examples 1-3 and Comparative Examples 1-3 are shown in Table 3 below.

[0091] Table 3

[0092]

[0093] Compared with Example 1, the cone penetration, flow rate and pumping rate of Comparative Example 1 did not change significantly, while the adhesion rate and filtration loss showed significant changes. Specifically, at 0°C, the adhesion rate of Example 1 was 80%, while the adhesion rate of Comparative Example 1 was only 32%, indicating that Comparative Example 1 could not be well attached to the tunnel segment wall and did not meet the adhesion rate performance requirements in Table 3; at 0°C, the filtration loss of Example 1 was 5.8g, while the filtration loss of Comparative Example 1 reached 17.6g, indicating that under the same water pressure, the loss rate of Comparative Example 1 was greater and the water pressure resistance sealing performance was poor.

[0094] Compared with Example 2, except for the density, other performance indicators in Comparative Example 2 have obvious changes. Specifically, at 0°C, the cone penetration, flow rate, pumping rate, adhesion rate, and filtration loss of Comparative Example 2 are reduced by 39%, 63%, 48%, 74%, and 34%, respectively. According to Table 3, except for the filtration loss, other properties of Comparative Example 2 cannot meet the performance requirements of the shield tail sealing grease.

[0095] Compared with Example 3, the cone penetration, flow rate and pumpability in Comparative Example 3 are significantly reduced, and the filtration loss is increased. The overall performance of Example 3 is poor, the shield tail grease produced is uneven, and lumps are prone to appear during the production process. It can be explained that butter as a lubricant is beneficial to improving the cone penetration, fluidity and pumpability of the shield tail sealing grease in addition to ensuring qualified water pressure sealing performance.

[0096] The results show that the shield tail sealing grease provided by the embodiment of the present invention has good consistency, fluidity, pumpability, adhesion and water pressure resistance and sealing performance at room temperature and low temperature conditions, meets the performance requirements of the shield tail sealing grease, can ensure the safety and smooth progress of shield construction, and has good application prospects.

[0097] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A low temperature resistant and stable shield tail sealing grease, characterized in that: The low temperature resistant and stable shield tail sealing grease comprises, by weight: Dispersed fiber 3.6-4.6 parts, viscosity regulator 9.7-10.5 parts, consistency regulator 0-25.5 parts, viscosity index improver 0-17.4 parts, lubricant 6.8-9.8 parts, filler 42.7-46.4 parts, water resistance enhancing filler 4.9-15.5 parts, thermal resistance filler 0-2.8 parts.

2. The low temperature resistant and stable shield tail sealing grease according to claim 1, characterized in that: The dispersed fibers are selected from one or both of wood fibers and polypropylene fibers.

3. The low temperature resistant and stable shield tail sealing grease according to claim 1, characterized in that: The viscosity modifier is selected from one or more of C5 petroleum resin, C9 petroleum resin and 150N mineral oil.

4. The low temperature resistant and stable shield tail sealing grease according to claim 1, characterized in that: The consistency regulator is selected from one or both of low-viscosity polyisobutylene and medium-viscosity polyisobutylene.

5. The low temperature resistant and stable shield tail sealing grease according to claim 1, characterized in that: The viscosity index improver is an ethylene-propylene copolymer.

6. The low temperature resistant and stable shield tail sealing grease according to claim 1, characterized in that: The lubricant is butter.

7. The low temperature resistant and stable shield tail sealing grease according to claim 1, characterized in that: The filler is selected from one or both of heavy activated calcium carbonate powder and light activated calcium carbonate powder.

8. The low temperature resistant and stable shield tail sealing grease according to claim 1, characterized in that: The water resistance enhancing filler is sodium bentonite.

9. The low temperature resistant and stable shield tail sealing grease according to claim 1, characterized in that: The thermal resistance filler is mica sheet.

10. The method for preparing the low temperature resistant and stable shield tail sealing grease according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) Add the dispersed fibers and the viscosity modifier into a kneader, control the inner wall temperature of the kneader to 80±5°C, and knead at a speed of 70±10 rpm until the dispersed fibers are in the form of fragments, more than 90% of the dispersed fibers are soaked in the viscosity modifier, and there is no obvious residual viscosity modifier at the bottom of the kneader; (2) Add consistency regulator, viscosity index improver and lubricant to the kneader, maintain the inner wall temperature of the kneader at 80±5°C, adjust the kneader speed to 80±20 rpm, knead for at least 40 min, and ensure that the surface color of the mixture is uniform and there is no obvious stratification. Randomly sample the product from the upper, middle and lower parts of the kneader. When the measured temperature reaches above 75°C, proceed to the next step. Otherwise, continue to increase the kneading time to meet this requirement. (3) Add water-resistant fillers and heat-resistant fillers to the kneader, maintain the inner wall temperature of the kneader at 80±5°C, adjust the kneader speed to 100±10 rpm, knead for at least 60 min, and ensure that the surface color of the mixture is uniform and there is no obvious stratification. Randomly sample the product from the upper, middle and lower parts of the kneader. When the measured temperature reaches above 75°C, proceed to the next step. Otherwise, continue to increase the kneading time to meet this requirement. (4) Add filler to the kneader, maintain the inner wall temperature of the kneader at 80±5°C, adjust the kneader speed to 120±10 rpm, and knead for at least 60 min. Divide the filler into 3 equal parts by total mass and add them in 3 times, with an interval of 10 to 15 minutes each time, until the mixture is beige in color and has no obvious stratification. Randomly sample the product from the upper, middle and lower parts of the kneader. When the measured temperature reaches above 75°C and there is no block with a diameter greater than 5 cm, proceed to the next step. Otherwise, continue to increase the kneading time to meet this requirement. (5) After naturally cooling to room temperature, the mixture is sealed and stored to obtain the low-temperature resistant and stable shield tail sealing grease.

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