Water-resistant sealing composite fiber material, preparation method thereof, water-resistant sealing shield tail sealing grease and application

Abstract

The invention provides a water-resistant sealing composite fiber material, a preparation method thereof, water-resistant sealing shield tail sealing grease and application. The preparation method of the water-resistant sealing composite fiber material comprises the following steps: carrying out acid pretreatment on basalt fibers, and then carrying out alkali neutralization to obtain pretreated basalt fibers; adding a silane coupling agent into a solvent, heating to 50-70 DEG C, and adding the pretreated basalt fibers for modification to obtain modified basalt fibers; the preparation method comprises the following steps: uniformly dispersing aromatic hydrocarbon petroleum resin and basalt modified fiber, adding a curing agent and an accelerant, uniformly stirring and mixing, curing and cooling to obtain an aromatic hydrocarbon petroleum resin / basalt modified fiber composite material; and mixing the aromatic hydrocarbon petroleum resin / basalt modified fiber composite material with an auxiliary fiber material to obtain the water-resistant sealing composite fiber material. The water-resistant sealing shield tail sealing grease prepared from the water-resistant sealing composite fiber material has good viscosity, sealing performance, pumping performance and water flushing resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lubricating grease, and particularly relates to a water-resistant sealing composite fiber material and a preparation method thereof, a water-resistant sealing shield tail sealing grease and application thereof. BACKGROUND

[0002] A shield tunneling machine (referred to as a shield machine) is one of the core equipments for tunnel construction, and is divided into a slurry shield machine and a soil pressure balance shield machine according to a shield method. In the shield construction process, with the tunneling of the shield machine, there is relative sliding between the shield tail and the already installed segment, and a shield tail sealing device must be installed between the shield tail and the segment. Shield tail sealing grease is one of the key supporting sealing and lubricating materials in the shield tunnel construction process, and has sealing and lubricating effects. In the starting and advancing process of the shield machine, the movement gap between the tunnel lining segment and the shield tail steel wire brush is generally 3-4 mm. In order to prevent external underground water and slurry from flowing into the shield tail, a certain pressure of the shield tail sealing grease is usually injected into the annular cavity located between the shield tail and the segment, fills the gap between the steel plate, the shield tail brush and the tunnel segment, and cooperates with the spring steel plate and the steel wire brush, so that the sealing function of the steel wire brush can be enhanced, and a firm sealing layer is formed, thereby preventing the infiltration of slurry, soil and mud, and guaranteeing the smooth advancement of the shield. Meanwhile, the dense grease layer formed between the sealing material and the steel plate and the segment can also play a role in preventing corrosion and reducing wear of the shield.

[0003] Therefore, the shield tail sealing grease not only requires appropriate density, cone penetration, good corrosion resistance, adhesion, structural stability and other physical and chemical properties, but also must have excellent sealing performance, water resistance and pumping performance and other key use performances. SUMMARY

[0004] To solve the above technical problems, the purpose of the present application is to provide a water-resistant sealing composite fiber material and a preparation method thereof, a water-resistant sealing shield tail sealing grease and application thereof.

[0005] To achieve the above purpose, the present application provides a preparation method of a water-resistant sealing composite fiber material, wherein the preparation method comprises the following steps:

[0006] (1) basalt fibers are subjected to acid pretreatment, then neutralized in alkali, and after centrifugation, pretreated basalt fibers are obtained;

[0007] (2) in a solvent, a silane coupling agent is added, heated to 50-70 DEG C, and the pretreated basalt fibers are modified to obtain basalt modified fibers;

[0008] (3) after the aromatic hydrocarbon petroleum resin and the basalt modified fibers are uniformly dispersed, a curing agent and an accelerator are added and uniformly stirred and mixed, and after curing and cooling, an aromatic hydrocarbon petroleum resin / basalt modified fiber composite material is prepared;

[0009] (4) Mix aromatic petroleum resin / basalt modified fiber composite material and auxiliary fiber material to obtain water-resistant sealing composite fiber material.

[0010] According to a specific embodiment of the present invention, preferably, in step (2), the amount of the silane coupling agent is 1.0%-5.0% based on 100% of the weight of the pretreated basalt fiber.

[0011] According to a specific embodiment of the present invention, preferably, the silane coupling agent is KH550 and the solvent is anhydrous ethanol.

[0012] The inventors of this invention discovered that due to the smooth surface and chemical inertness of basalt fibers, the interfacial adhesion between the basalt fiber surface and the shield tail sealant material is poor, failing to fully utilize the advantages of basalt fibers. Therefore, this invention uses a silane coupling agent to modify the surface of basalt fibers. Furthermore, since the reaction between the silane coupling agent KH550 and basalt fibers in anhydrous ethanol in step (2) involves chemical bonding and surface modification, temperature directly affects the activity and reaction rate of the silane coupling agent, making this process highly sensitive to temperature control. If the reaction temperature is below 50°C, the following effects may occur: ① Since the reaction between the silane coupling agent and the basalt fiber surface is endothermic, the reaction rate will slow down at low temperatures, leading to incomplete reaction and potentially poor surface modification of the fibers; ② Since the silane coupling agent needs a certain temperature to reach its optimal activity state, low temperatures may result in insufficient activity, preventing a sufficient chemical reaction with the basalt fiber surface. If the reaction temperature exceeds 70℃, the following effects may occur on the reaction: ① Excessive temperature may cause the silane coupling agent to decompose, causing it to lose its ability to react with basalt fibers, and may even produce byproducts that are harmful to fiber properties; ② High temperature may cause the reaction to be too violent and difficult to control, and may even cause safety risks such as explosion; ③ Anhydrous ethanol solvent is prone to rapid volatilization at high temperatures, which will not only affect the uniformity and stability of the reaction, but may also cause the silane coupling agent to concentrate prematurely on the fiber surface, thereby affecting the modification effect.

[0013] According to a specific embodiment of the present invention, preferably, in step (3), the amount of basalt modified fiber is 1%-4% based on the weight of aromatic petroleum resin as 100%.

[0014] According to a specific embodiment of the present invention, preferably, in step (4), based on the weight of the water-resistant sealing composite fiber material as 100%, the content of the aromatic petroleum resin / basalt modified fiber composite material is 5%-75%, and the content of the auxiliary fiber material is 25%-95%. More preferably, the content of the aromatic petroleum resin / basalt modified fiber composite material is 5%-50%, and the content of the auxiliary fiber material is 50%-95%.

[0015] According to a specific embodiment of the present invention, preferably, the aromatic petroleum resin has a tensile strength of 120.5 MPa-125.5 MPa, an elongation at break of 8.5%-10.5%, a temperature at which it loses 5% of its weight at 200℃-400℃, a glass transition temperature of 145℃-155℃, and a melt index of 1-50 g / 10 min.

[0016] According to a specific embodiment of the present invention, preferably, the aromatic petroleum resin is polymerized from an olefin or cycloolefin containing nine carbon atoms; or, the aromatic petroleum resin is copolymerized from a polymeric olefin containing nine carbon atoms and other compounds, wherein the other compounds include one or more combinations of aldehyde compounds, aromatic compounds, terpenoid compounds, etc.

[0017] The inventors of this invention have discovered that the aromatic petroleum resin selected in this invention exhibits better mechanical, thermal, and processing properties compared to other types of petroleum resins, as shown in Tables 1, 2, and 3. This is due to the composition of the aromatic petroleum resin. Polymeric olefins are the main component of aromatic petroleum resins, including nine-carbon olefins such as 1-octene and cyclooctene. These olefins form long-chain structures through polymerization reactions, providing the basic framework for the resin. Aromatic compounds, containing benzene ring structures, can increase the aromaticity and stability of the resin, thereby affecting its physical and chemical properties and playing an important role in aromatic petroleum resins. Aldehydes can copolymerize with olefins or aromatics, participating in the formation of the aromatic petroleum resin structure. Introducing aldehydes can alter the resin's polarity, solubility, and other properties. Terpenes, a class of natural compounds with distinctive aromas, can also participate in the synthesis of aromatic petroleum resins, increasing their aroma and certain special properties, such as compatibility or weather resistance. Furthermore, the superior mechanical properties of aromatic petroleum resins (such as high tensile strength and elongation at break) enable aromatic petroleum resin / basalt-modified fiber composites to provide better sealing performance and durability when used as sealants. The high thermal stability and thermogravimetric temperature of aromatic petroleum resins prevent thermal decomposition or softening of the composites at high temperatures, ensuring the stability and reliability of the sealant at high temperatures. The good processing properties of aromatic petroleum resins (such as low melt index and suitable viscosity) make the composites easy to process and mold during preparation, thus facilitating the production of high-quality sealant products. Therefore, this invention, by curing aromatic petroleum resins and basalt-modified fibers under certain conditions, prepares an aromatic petroleum resin / basalt-modified fiber composite, which effectively overcomes the problems of poor adhesion between traditional fibers and polymers in sealants, low thermal stability, and high chemical hygroscopicity.

[0018] Table 1. Test results of mechanical properties of different types of petroleum resins

[0019]

[0020]

[0021] Table 2. Thermal performance test results of different types of petroleum resins

[0022] Petroleum resin type Temperature at 5% thermal weight loss (°C) Glass transition temperature (°C) Aromatic petroleum resin 280 150 Aliphatic petroleum resin 250 135 Naphthenic petroleum resin 265 140

[0023] Table 3. Test results of processing properties of different types of petroleum resins

[0024] Petroleum resin type Melt index (g / 10 min) Spinning uniformity Aromatic petroleum resin 12.5 Excellent Aliphatic petroleum resin 10.0 Fair Naphthenic petroleum resin 11.0 Fair

[0025] According to a specific embodiment of the present invention, preferably, the amount of curing agent is 1%-3% and the amount of accelerator is 1%-5% based on 100% of the weight of the pretreated basalt fiber.

[0026] According to a specific embodiment of the present invention, preferably, the curing agent is methyltetrahydrophthalic anhydride; and the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0027] According to a specific embodiment of the present invention, preferably, the curing temperature is 60-80℃ and the curing time is 2-4h.

[0028] According to a specific embodiment of the present invention, preferably, the auxiliary fiber material includes one or more of wood fiber, ramie fiber, polypropylene fiber, etc.

[0029] According to a specific embodiment of the present invention, preferably, the auxiliary fiber is ramie fiber, and the mass ratio of the aromatic petroleum resin / basalt modified fiber composite material to the ramie fiber is 5:2 to 1:3, more preferably 1:2 to 1:3. The addition of ramie fiber can improve the impact resistance and permeability of the product.

[0030] According to a specific embodiment of the present invention, preferably, the length of the aromatic petroleum resin / basalt modified fiber composite material is 5-20 mm; the length of the auxiliary fiber is 1.5-4 mm, more preferably 1.5-2.5 mm; and the fiber diameter of the water-resistant sealing composite fiber material is 10-30 μm. The water-resistant sealing composite fiber material is a non-metallic fiber. When used in shield tail sealant, the hydroxyl groups on the fiber surface form hydrogen bonds, which stabilize the skeleton and thus ensure the sealing performance of the sealant in a wet environment. If the fiber is too short, the overall skeleton of the shield tail sealant is loose and the stability is poor; if the fiber is too long, the pumpability and flowability of the shield tail sealant are poor.

[0031] According to a specific embodiment of the present invention, preferably, the above preparation method specifically includes the following steps:

[0032] (1) Add basalt fibers to a 1.5-2.5 mol / L dilute hydrochloric acid or nitric acid aqueous solution, stir and react at room temperature for 2 hours, wash with sodium hydroxide aqueous solution until neutral, and centrifuge to obtain pretreated basalt fibers;

[0033] (2) Add silane coupling agent KH550 to anhydrous ethanol solvent, stir evenly, heat to 50-70℃, add pretreated basalt fiber, stir and disperse for more than 2 hours, centrifuge to wash away unreacted silane coupling agent KH550, dry to obtain basalt modified fiber.

[0034] (3) After the aromatic petroleum resin and basalt modified fiber are evenly dispersed, a curing agent and an accelerator are added, and the mixture is stirred and mixed evenly at room temperature. After curing and cooling, the aromatic petroleum resin / basalt modified fiber composite material is obtained.

[0035] (4) Mix aromatic petroleum resin / basalt modified fiber composite material and auxiliary fiber material to obtain water-resistant sealing composite fiber material.

[0036] The present invention also provides a water-resistant sealing composite fiber material, which is obtained by the above preparation method.

[0037] The present invention also provides a water-resistant sealing shield tail grease, the raw materials of which include the above-mentioned water-resistant sealing composite fiber material; wherein, based on the total mass of the raw materials of the shield tail grease being 100%, the raw materials of the shield tail grease include: 15%-30% mixed base oil (preferably 25%-30%), 20%-35% thickener, 5%-15% adhesive, 5%-20% water-resistant sealing composite fiber material, 5%-10% water-absorbing and swelling material, and 3.2%-7.5% additives; the sum of the mass percentages of all raw materials is 100%.

[0038] According to a specific embodiment of the present invention, preferably, the mixed base oil includes one or more of the following: paraffinic base oil, intermediate base oil, naphthenic base oil, polyalphaolefin, alkylnaphthalene, trimethylolpropane ester, pentaerythritol ester, dipentaerythritol ester, etc.

[0039] In some specific embodiments, preferably, the mixed base oil consists of intermediate base oil MVI 150 and polyalphaolefin PAO 100; wherein the mass ratio of intermediate base oil MVI 150 to polyalphaolefin PAO 100 is 3:1 to 1:1. Intermediate base oil MVI 150 refers to a medium viscosity index neutral oil with a viscosity grade of 150, suitable for lubricants requiring a balance between fluidity and viscosity retention; polyalphaolefin PAO 100 refers to a synthetic base oil with a viscosity grade of 100, possessing excellent thermal and oxidative stability, and providing better lubrication performance and longer service life when used in high-performance lubricants and greases.

[0040] In some specific embodiments, preferably, the MVI 150 base oil has a viscosity of 28-34 mm at 40°C. 2 / s, pour point not higher than -10℃, open flash point not lower than 170℃, oxidation stability (rotating bomb method, 150℃) not less than 180min.

[0041] In some specific embodiments, preferably, the viscosity of the PAO 100 base oil at 100°C is 97-105 mm.2 / s, pour point not higher than -30℃, open flash point not lower than 200℃, oxidation stability (rotating bomb method, 150℃) not less than 400min.

[0042] According to a specific embodiment of the present invention, preferably, the thickener includes one or a combination of two or more of the following: light calcium carbonate, light magnesium carbonate, heavy calcium carbonate, talc, mica powder, fumed silica, and kaolin.

[0043] In some specific embodiments, preferably, the thickener is composed of light calcium carbonate, organobentonite, talc, mica powder, and fumed silica; wherein, based on the mass of light calcium carbonate, the content of organobentonite is 0.5-5 times that of light calcium carbonate, the content of talc is 0.5-4 times that of light calcium carbonate, the content of mica powder is 0.2-1 times that of light calcium carbonate, and the content of fumed silica is 1-5 times that of light calcium carbonate.

[0044] The inventors of this invention have discovered that light calcium carbonate possesses characteristics such as non-toxicity, good dispersibility, stable framework, improved rheology, and enhanced tear strength. As a basic framework material, light calcium carbonate provides excellent dispersibility and stability, constructing a robust framework for the composite system. This not only enhances the structural strength of the entire system but also provides effective support and a dispersion platform for other components. In organobentonite, the lamellar structure of montmorillonite swells and disperses into colloidal particles in water or organic solvents, providing excellent thickening and thixotropic properties to the system. Simultaneously, organobentonite exhibits good thickening, thixotropic, suspension stability, high-temperature stability, lubricity, film-forming properties, water resistance, and chemical stability, contributing to improved processability and final product performance. Through synergistic effects with light calcium carbonate, bentonite can further enhance the framework stability of the system. Talc, with its non-toxic and easily dispersible properties, enhances the skeletal stability of the system and improves the tensile and shear strength of the product. It is commonly used in rubber and plastic materials as a reinforcing material to increase tensile strength, shear strength, and flame retardancy. The interaction of talc with other components, especially organobentonite and light calcium carbonate, helps to construct a more compact and uniform structure. Mica powder possesses good flame retardancy, elasticity, flexibility, and adhesive strength. The addition of mica powder not only improves the flame retardant properties of the system, but its high viscosity and consistency in water also enhance the overall thickening effect. The elasticity and flexibility of mica powder complement the rigid structure of other components, resulting in a final product with better film mechanical strength and adhesion. Fumed silica is non-toxic, odorless, and pollution-free. Its surface contains silanol groups and silanol groups, with the silanol groups exhibiting high surface activity. These silanol groups can form hydrogen bonds or react with other groups, ensuring a stable three-dimensional network structure between silica particles. This provides the system with properties such as reinforcement, toughening, thickening, thixotropy, and anti-settling. The interaction between fumed silica and other components, particularly with mica powder, further enhances the system's stability and flowability. The inventors of this invention have discovered that the combined use of the above five solid thickeners can form an elastomer-based water-resistant sealing tape, especially when containing mica powder and fumed silica. This not only avoids acid-base reactions and corrosion when the sealant encounters acidic or alkaline compounds during use but also improves the sealant's stability and flowability, further preventing hardening and solidification. This ensures the sealant's adhesion, pumpability, sealing properties, and lubrication during use.

[0045] In some specific embodiments, preferably, the average primary particle size of the fumed silica is 7-40 μm, and the specific surface area is 50-380 m². 2 / g, SiO2 content greater than 99.8%.

[0046] According to a specific embodiment of the present invention, preferably, the adhesive includes one or more of polyisobutylene, polymethacrylate, coumarone resin, polyethylene, polypropylene, ethylene-propylene copolymer, etc.

[0047] In some specific embodiments, preferably, the adhesive is composed of polyisobutylene and ethylene-propylene copolymer; wherein the mass ratio of polyisobutylene to ethylene-propylene copolymer is 2:1 to 1:3, more preferably 1:2 to 1:3.

[0048] In some specific embodiments, preferably, the ethylene content in the ethylene-propylene copolymer ranges from 10% to 90%, more preferably from 15% to 30%. More preferably, the molecular weight of the ethylene-propylene copolymer ranges from 50,000 to 200,000 Daltons. The addition of polyisobutylene and ethylene-propylene copolymer adhesives increases the viscosity and cohesiveness of the fibers and base oil, improving the grease's viscosity; simultaneously, it enhances the product's adhesion, hydrophobicity, sealing properties, and water resistance, effectively preventing external water and mud from seeping into gaps, ensuring the shield tail sealant's anti-leakage, adhesion, and lubrication performance in wet environments.

[0049] According to a specific embodiment of the present invention, preferably, the water-absorbing and swelling material includes one or more of the following: high-sodium bentonite, sodium polyacrylate, carboxymethyl cellulose, polyvinyl alcohol, hydrophilic polyurethane prepolymer, acrylonitrile-vinyl acetate copolymer, polyvinyl alcohol and dipropylene ester crosslinker, and anionic polyacrylamide.

[0050] In some specific embodiments, preferably, the water-absorbing and swelling material is composed of sodium polyacrylate and carboxymethyl cellulose; wherein the mass ratio of sodium polyacrylate to carboxymethyl cellulose is 2:1 to 1:2. The combined use of sodium polyacrylate and carboxymethyl cellulose water-absorbing and swelling materials, through their inherent water-absorbing and swelling properties, can produce a significant water-resistant sealing effect. The inventors of this invention have discovered that using sodium polyacrylate and carboxymethyl cellulose as water-absorbing and swelling materials, under the synergistic effect of a water-stabilizing chelating agent, can produce a significant water-resistant sealing effect; simultaneously, under the action of antioxidants and rust inhibitors, a dense grease protective layer can be formed between the steel plate and the tunnel segments, which can prevent shield corrosion and reduce wear.

[0051] According to a specific embodiment of the present invention, preferably, the particle size of the water-absorbing and swelling material is less than 50 μm, more preferably 15-30 μm, so as to overcome the problem that the water-absorbing and swelling material is easy to peel off after being mixed with the shield tail sealant.

[0052] According to a specific embodiment of the present invention, preferably, based on the total mass of the raw materials of the shield tail sealant as 100%, the additives include: 1.5%-2.5% rust inhibitor (preferably 2.0%), 1.5%-2.5% water stabilizer chelating agent (preferably 2.0%), and 0.2%-2.5% antioxidant (preferably 2.0%).

[0053] In some specific embodiments, preferably, the rust inhibitor includes one or a combination of two or more of benzimidazole derivatives, sodium petroleum sulfonate, stearic acid, oleic acid, pentaerythritol monooleate, and sorbitan monooleate. The benzimidazole derivatives include 2-mercaptobenzimidazole, etc.

[0054] In some specific embodiments, preferably, the rust inhibitor is composed of 2-mercaptobenzimidazole and sodium petroleum sulfonate; wherein the mass ratio of 2-mercaptobenzimidazole to sodium petroleum sulfonate is 1:1.5.

[0055] In some specific embodiments, preferably, the water-stabilized chelating agent is an organic acid and / or salt substance, including one or more of sodium tripolyphosphate, sodium gluconate, ethylenediaminetetraacetic acid, tetrasodium ethylenediaminetetraacetic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, etc.

[0056] In some specific embodiments, preferably, the water-stabilized chelating agent is composed of sodium tripolyphosphate and ethylenediaminetetramethylenephosphonic acid; wherein the mass ratio of sodium tripolyphosphate to ethylenediaminetetramethylenephosphonic acid is 2:1 to 1:2.

[0057] In some specific embodiments, preferably, the antioxidant includes one or a combination of two or more of 2',6-di-tert-butyl-p-cresol, octyl diphenylamine, dipentyl dithiocarbamate, etc.

[0058] In some specific embodiments, preferably, the antioxidant is composed of 2',6-di-tert-butyl-p-cresol and octyl diphenylamine; wherein the mass ratio of 2',6-di-tert-butyl-p-cresol and octyl diphenylamine is 1:1.

[0059] This invention also provides the application of the above-mentioned water-resistant sealing shield tail sealant in the field of shield tunneling construction.

[0060] According to a specific embodiment of the present invention, preferably, the preparation method of the water-resistant sealing shield tail sealant includes the following steps:

[0061] (a) At room temperature, the base oil and thickener are added to a mixer and mixed for 30 minutes, and the temperature is gradually increased to 60-90℃ to obtain mixture a;

[0062] (b) Add the water-resistant sealing composite fiber material to the already mixed mixture a, keep it at 60-90℃, stir thoroughly for 1-3 hours until it is completely mixed to obtain mixture b;

[0063] (c) Add the adhesive to mixture b, keep warm at 60-90℃, stir thoroughly for 1-3 hours until completely mixed and homogeneous, to obtain mixture c;

[0064] (d) Add water-absorbing and swelling materials and additives to mixture c, keep warm at 60-90℃, stir for 40-120 minutes and then discharge. After sampling and testing, the product is packaged to obtain water-resistant sealing shield tail sealant.

[0065] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0066] (1) The anti-water sealing shield tail seal grease provided by the present invention uses an anti-water sealing composite fiber material prepared by mixing aromatic petroleum resin / basalt modified fiber composite material in a specific ratio, which replaces the traditional wood fiber, ramie fiber and polypropylene fiber. This solves the problems of lubricant dispersion and loss, insufficient pressure resistance and sealing failure caused by the easy dilution and dissolution of the anti-water sealing composite fiber material during use. In addition, while maintaining good pumpability, it improves the impact resistance and permeability of the product.

[0067] (2) This invention uses different thickener components in a compound formulation. Due to the synergistic effect between the thickener components, the stability of the entire system is greatly improved. Furthermore, although the system contains multiple thickeners, the synergistic effect between the components allows the sealant to maintain its consistency while retaining good fluidity, making it easy to pump and apply. Simultaneously, through the compound use of the various thickener components, the sealant's adhesion, sealing properties, and lubricity are significantly improved, enabling it to maintain a good sealing effect in various environments. Detailed Implementation

[0068] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0069] Unless otherwise specified, the reagents or instruments used in the embodiments of this invention are all commercially available conventional reagent products.

[0070] The preparation method of the water-resistant and sealing composite fiber material used in the embodiments of the present invention includes the following steps:

[0071] (1) Basalt fibers were added to a 2.0 mol / L dilute hydrochloric acid aqueous solution and stirred at room temperature for 2 hours. After washing with sodium hydroxide (NaOH) aqueous solution until neutral, the pretreated basalt fibers were obtained by centrifugation.

[0072] (2) Add silane coupling agent KH 550 (2.5% by weight of the pretreated basalt fiber) to anhydrous ethanol solvent and stir until homogeneous. Then heat to 60°C, add the pretreated basalt fiber, stir and disperse for 3 hours, centrifuge to wash away unreacted silane coupling agent KH550, and dry to obtain basalt modified fiber.

[0073] (3) Taking the mass of aromatic petroleum resin as 100%, the aromatic petroleum resin and basalt modified fiber (mass fraction of 3.0%) are mixed and dispersed evenly. Then, the curing agent methyltetrahydrophthalic anhydride (mass fraction of 2%) and the accelerator 2,4,6-tris(dimethylaminomethyl)phenol (mass fraction of 3%) are added. The mixture is stirred and mixed evenly at room temperature and cured under the curing conditions of 65°C for 2.5 hours. After cooling, the aromatic petroleum resin / basalt modified fiber composite material is obtained.

[0074] (4) Based on the total weight of the water-resistant sealing composite fiber, the aromatic petroleum resin / basalt modified fiber composite material and ramie fiber were mixed in different proportions as shown in Table 5 to obtain the water-resistant sealing composite fiber.

[0075] Modification with silane coupling agents can improve the properties of basalt fibers in the following aspects:

[0076] ① Improve the microstructure and chemical structure of the fiber surface:

[0077] The adhesion of silane coupling agents to the surface of basalt fibers can make them rougher and leave residues, which can make the fiber bundles more dispersed. This is beneficial for the resin to better penetrate into the gaps between the fibers and increase the wetting ability of the resin matrix on the fiber surface.

[0078] ② Improve the mechanical properties of fiber-reinforced composite materials:

[0079] Composite materials were prepared by mixing basalt fibers modified with silane coupling agents and unmodified basalt fibers with a resin matrix. Bending strength and impact strength were then tested, and the results are shown in Table 4.

[0080] Table 4. Mechanical properties of fibers before and after modification

[0081] Fiber type Bending strength (MPa) Impact strength (kJ / m 2 ) Unmodified 600 30 After modification 750 (25% increase) 40 (33% increase)

[0082] Experimental data show that modification with a silane coupling agent significantly improves the interfacial bonding between basalt fibers and resin, thereby increasing the flexural strength and impact strength of the composite material. Specifically, the flexural strength and impact strength of the basalt fiber-reinforced composite material modified with a specific silane coupling agent are significantly improved compared to the unmodified fiber.

[0083] ③ Improve the corrosion resistance of fibers:

[0084] The introduction of silane coupling agents can also improve the corrosion resistance of basalt fibers in acidic and alkaline media. After soaking in a 10% sulfuric acid solution for 24 hours, the mass loss of unmodified fibers was 1.5%, while the mass loss of fibers modified with 0.5% silane coupling agent was only 0.8%. The corrosion resistance of the fibers also showed a significant improvement with increasing concentration of the silane coupling agent.

[0085] Examples 1-4

[0086] Examples 1-4 provide a water-resistant sealing shield tail sealant containing a water-resistant sealing composite fiber material. The components and their mass fractions are shown in Table 5, with the weight of the shield tail sealant as 100%.

[0087] Table 5. Components and mass fractions of Examples 1-4

[0088]

[0089]

[0090] The preparation method of the water-resistant sealing shield tail sealant in Example 1 includes the following steps:

[0091] (a) According to the component ratio in Table 5, mix the base oil and thickener for 30 min and gradually heat to 60°C to obtain mixture a;

[0092] (b) Add the water-resistant sealing composite fiber material to mixture a according to the component ratio in Table 5, keep it at 60°C, stir for 1 hour until it is completely mixed and homogeneous to obtain mixture b;

[0093] (c) Add the adhesive to mixture b according to the component ratio in Table 5, keep warm at 60°C, stir for 1 hour until completely mixed and homogeneous to obtain mixture c;

[0094] (d) According to the component ratio in Table 5, add water-absorbing and expanding materials and additives to mixture c, keep it at 60°C, stir for 40 minutes and then discharge to obtain water-resistant sealing shield tail sealant.

[0095] The preparation method of the water-resistant sealing shield tail sealant in Example 2 includes the following steps:

[0096] (a) According to the component ratio in Table 5, mix the base oil and thickener for 30 min and gradually heat to 70°C to obtain mixture a;

[0097] (b) According to the component proportions in Table 5, add the water-resistant sealing composite fiber material to mixture a, keep it at 70°C, stir for 1.5 hours until it is completely mixed and homogeneous to obtain mixture b;

[0098] (c) According to the component proportions in Table 5, add the adhesive to mixture b, keep warm at 70°C, stir for 1.5 hours until completely mixed and homogeneous to obtain mixture c;

[0099] (d) According to the component ratio in Table 5, add water-absorbing and expanding materials and additives to mixture c, keep it at 70°C, stir for 60 minutes and then discharge to obtain water-resistant sealing shield tail sealant.

[0100] The preparation method of the water-resistant sealing shield tail sealant in Example 3 includes the following steps:

[0101] (a) According to the component ratio in Table 5, mix the base oil and thickener for 30 min and gradually heat to 85°C to obtain mixture a;

[0102] (b) Add the water-resistant sealing composite fiber material to mixture a according to the component ratio in Table 5, keep it at 85°C, stir for 2 hours until it is completely mixed and homogeneous to obtain mixture b;

[0103] (c) Add the adhesive to mixture b according to the component proportions in Table 5, keep warm at 85°C, stir for 2 hours until completely mixed and homogeneous to obtain mixture c;

[0104] (d) According to the component proportions in Table 5, add water-absorbing and expanding materials and additives to mixture c, keep it at 85°C, stir for 70 minutes and then discharge to obtain water-resistant sealing shield tail sealant.

[0105] The preparation method of the water-resistant sealing shield tail sealant in Example 4 includes the following steps:

[0106] (a) According to the component ratio in Table 5, mix the base oil and thickener for 30 min and gradually heat to 90°C to obtain mixture a;

[0107] (b) Add the water-resistant sealing composite fiber material to mixture a according to the component ratio in Table 5, keep it at 90°C, stir for 3 hours until it is completely mixed and homogeneous to obtain mixture b;

[0108] (c) Add the adhesive to mixture b according to the component ratio in Table 5, keep warm at 90°C, stir for 3 hours until completely mixed and homogeneous to obtain mixture c;

[0109] (d) According to the component ratio in Table 5, add water-absorbing and expanding materials and additives to mixture c, keep it at 90°C, stir for 120 min and then discharge to obtain water-resistant sealing shield tail sealant.

[0110] Comparative Examples 1-4

[0111] Comparative Examples 1-4 provide a shield tail sealant, the preparation process of which is similar to that of the examples, except that the composition and weight percentage of the shield tail sealant are changed; based on the weight of the shield tail sealant as 100%, the components and mass fractions are shown in Table 6:

[0112] Table 6. Components and mass fractions of Comparative Examples 1-4

[0113]

[0114]

[0115] Among them, Comparative Example 4 is TD-BS268 shield tail sealing grease produced by Beijing Guofutongtai Technology Co., Ltd.

[0116] The shield tail sealing greases obtained in Examples 1-4 and Comparative Examples 1-4 were tested in different aspects. The test process and results are as follows:

[0117] Test Example 1: Basic Physicochemical Properties Test

[0118] The shield tail sealing greases obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to basic physicochemical property tests in accordance with the technical requirements and test methods of T / CPCIF 0042.1-2020 "Shield Sealing Grease Series Products and Test Methods Part 1 Shield Tail Sealing Grease". The results are shown in Tables 7 and 8.

[0119] Table 7. Comparison of Analytical Test Data

[0120]

[0121]

[0122] Table 8. Comparison of Analysis and Test Data (Continued)

[0123]

[0124] According to the data in Tables 7 and 8, when the total content of each additive is the same, adjusting the usage ratio of base oil, thickener, adhesive, fiber material, water-absorbing and swelling material and additives, as shown in Examples 1-4, the prepared water-resistant sealing shield tail grease exhibits excellent performance in basic physicochemical properties such as appearance, non-working cone penetration, oil separation amount and evaporation loss. Compared with the commercially available product Comparative Example 4, these properties are improved, but they are basically at the same level as the comparative example.

[0125] However, the key to sealing grease products lies in whether they can meet the equipment's critical performance requirements during application. For example, the sealing grease must possess good adhesion, water resistance, pumpability, and water spray resistance. Therefore, further testing will be conducted on these key performance aspects below.

[0126] Test Example 2 Adhesion Test

[0127] The shield tail sealant greases obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to adhesion tests according to Appendix B of T / CPCIF 0042.1-2020 "Shield Sealing Grease Series Products and Test Methods Part 1 Shield Tail Sealant". This method involves measuring the maximum distance the sample extends beyond the mold front end after 24 hours at a temperature of 25°C and an air pressure of 1 MPa, i.e., the creep distance, expressed in mm. The adhesion test results for different shield tail sealant greases are shown in Table 9.

[0128] Table 9. Results of adhesion performance tests for different shield tail sealants

[0129]

[0130]

[0131] Adhesion can be used to characterize the bonding performance between the tail sealant and the metal surface. The amount of fiber, the type of fiber material, the thickener, and the adhesive all have a significant impact on the adhesion of the tail sealant. The test results of Examples 1 and 2 in Table 9 show that reducing the amount of organobentonite and mica powder in the thickener, increasing the amount of talc powder, and adjusting the ratio of aromatic petroleum resin / basalt modified fiber composite material and ramie fiber in the water-resistant sealing composite material all increase the creep distance of the tail sealant. This indicates that its adhesion gradually weakens as the amount of organobentonite and mica powder decreases, and gradually weakens as the amount of talc powder increases.

[0132] This is mainly because the lamellar structure of montmorillonite in bentonite can swell and disperse into colloidal particles in water or organic solvents, exhibiting good thickening properties, high-temperature stability, lubricity, and water resistance. Simultaneously, the addition of mica powder enhances the flexibility and adhesion of the sealant, improving product adhesion. Therefore, as the amount of organic bentonite and mica powder decreases, the adhesion of the shield tail sealant weakens.

[0133] Test Example 3: Water Resistance and Sealing Test

[0134] The shield tail sealant obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to water resistance sealing tests according to the evaluation requirements of Appendix C of T / CPCIF 0042.1-2020 "Shield Sealing Grease Series Products and Test Methods Part 1 Shield Tail Sealant". The test results of water resistance sealing of different shield tail sealants are shown in Table 10.

[0135] Table 10. Comparison of water resistance and sealing test results for different shield tail sealants

[0136] Gasket type Water leakage from grease hole and inner wall Grease leakage amount / g Example 1 No water 2.8 Example 2 No water 3.2 Example 3 No water 0.8 Example 4 No water 1.4 Comparative Example 1 No water 4.0 Comparative Example 2 No water 4.5 Comparative Example 3 No water 6.8 Comparative Example 4 No water 3.5

[0137] Water resistance sealing performance is used to characterize the sealing performance of the tail sealant. The test results of Examples 1 and 2 in Table 10 show that reducing the amount of organic bentonite and mica powder in the thickener increases the leakage of the tail sealant, leading to a decrease in its water resistance sealing performance. This is basically consistent with the change in the adhesion of the tail sealant.

[0138] The test results from Examples 1 and 4 show that adjusting the ratio of water-absorbing swelling agent and water-stabilizing chelating agent, and appropriately increasing the content of carboxymethyl cellulose and ethylenediaminetetramethylenephosphonic acid, can significantly reduce the leakage of the shield tail sealant, thereby improving its water resistance and sealing performance. This is mainly because the inherent water absorption, swelling, and water stabilization properties of the water-absorbing swelling agent and water-stabilizing chelating agent produce a significant water-resistant sealing effect.

[0139] The test results from Examples 1 and 3 show that adjusting the ratio of adhesive and water-resistant sealing composite material components, and increasing the content of polyisobutylene and aromatic petroleum resin / basalt modified fiber composite material, can significantly reduce the leakage of the shield tail sealant, thereby improving its water resistance and sealing performance. This is mainly because adding a certain amount of plant, mineral, or synthetic fibers to the shield tail sealant can act as a skeleton in the sealant, improving its anti-permeability under high water pressure, thus ensuring its water resistance and sealing performance. The test results from Example 3 show that, with a fixed total amount of fiber material, increasing the content of aromatic petroleum resin / basalt modified fiber composite material makes the fibers distributed more uniformly in the system and the resulting three-dimensional fiber network denser. Simultaneously, the oleophilic components such as aromatic petroleum resin and polyolefin tackifiers in the shield tail sealant can also be more tightly connected through the basalt modified fibers, ultimately forming a uniform and fine network structure, thereby improving the water resistance and sealing performance of the shield tail sealant.

[0140] Test Example 4 Pumpability Test

[0141] The shield tail sealing greases obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to pumpability tests according to the evaluation requirements in Appendix D of T / CPCIF 0042.1-2020 "Shield Sealing Grease Series Products and Test Methods Part 1 Shield Tail Sealing Grease". This method involves measuring the flow rate through a capillary tube of a certain diameter at a temperature of 25°C and an air pressure of 1 MPa, expressed in g / min. The pumpability test results for different shield tail sealing greases are shown in Table 11.

[0142] Table 11. Pumping performance test results of different shield tail sealing greases

[0143]

[0144]

[0145] As can be seen from the data in Table 11, the pumpability of the products is greater than 40g / min, which meets the performance requirements.

[0146] Furthermore, the adhesiveness and pumpability of a product can affect each other in practical applications. Excessive adhesiveness can increase resistance during pumping, thus reducing pumpability. This is because excessive adhesion makes it more difficult for the sealant to flow through pipes or seals. On the other hand, if pumpability is too good but adhesiveness is insufficient, while it may be easy to pump, it may negatively impact the durability of the seal, as the sealant may not adhere tightly to the sealing surface.

[0147] Test Example 5: Water Spray Resistance Test

[0148] The shield tail sealing greases obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to water spray resistance tests according to the requirements of SH / T 0643 in T / CPCIF 0042.1-2020 "Shield Sealing Grease Series Products and Test Methods Part 1 Shield Tail Sealing Grease". The water spray resistance test conditions were as follows: the grease was applied to a stainless steel plate, and the sample was continuously rinsed with water for 5 minutes at a temperature of 38°C and a water pressure of 276 kPa. The percentage of weight loss due to spraying was measured as the measure of the grease's water spray resistance. The results of the water spray resistance tests for different shield tail sealing greases are shown in Table 12.

[0149] Table 12. Results of water spray resistance test for different shield tail sealants

[0150] Gasket type Spray weight loss percentage / % Example 1 4.6 Example 2 5.8 Example 3 3.3 Example 4 4.3 Comparative Example 1 4.5 Comparative Example 2 5.9 Comparative Example 3 4.7 Comparative Example 4 4.8

[0151] The test results of Examples 2, 3 and Comparative Example 2 in Table 12 show that the water spray resistance of the shield tail sealant is positively correlated with the adhesion of the shield tail sealant.

[0152] In summary, the present invention utilizes basalt-modified fibers in aromatic petroleum resin / basalt-modified fiber composite materials to overcome the shortcomings of traditional fiber materials, such as poor adhesion to polymers, low thermal stability, and high chemical hygroscopicity. The prepared water-resistant sealing shield tail sealant has a more uniform fiber distribution and a denser three-dimensional fiber network structure. This allows for the full and tight binding of oleophilic components such as aromatic petroleum resin and polyolefin tackifiers, as well as solid fillers such as organic bentonite, mica powder, and talc powder, forming a uniform and dense three-dimensional network embedded structure. This improves the key performance characteristics of the water-resistant sealing shield tail sealant, including structural stability, adhesion, water-resistant sealing performance, pumpability, and water spray resistance.

Claims

1. A method for preparing a water-resistant and sealing composite fiber material, wherein, The preparation method includes the following steps: (1) Basalt fibers are pretreated with acid, then neutralized with alkali, and centrifuged to obtain pretreated basalt fibers. (2) Add silane coupling agent to solvent, heat to 50-70℃, add pretreated basalt fiber for modification, and obtain basalt modified fiber; (3) After the aromatic petroleum resin and basalt modified fiber are evenly dispersed, a curing agent and an accelerator are added and stirred evenly. After curing and cooling, the aromatic petroleum resin / basalt modified fiber composite material is obtained. (4) Mix aromatic petroleum resin / basalt modified fiber composite material and auxiliary fiber material to obtain water-resistant sealing composite fiber material; In step (2), the amount of silane coupling agent used is 1.0%-5.0% based on the weight of the pretreated basalt fiber as 100%. In step (3), the amount of basalt modified fiber is 1%-4% based on the weight of aromatic petroleum resin as 100%. In step (4), the content of the aromatic petroleum resin / basalt modified fiber composite material is 5%-75% based on the weight of the water-resistant sealing composite fiber material as 100%, and the content of the auxiliary fiber material is 25%-95%.

2. The preparation method according to claim 1, wherein, The aromatic petroleum resin has a tensile strength of 120.5 MPa-125.5 MPa, an elongation at break of 8.5%-10.5%, a temperature at which it loses 5% of its weight at 200℃-400℃, a glass transition temperature of 145℃-155℃, and a melt index of 1-50 g / 10 min.

3. The preparation method according to claim 1, wherein, The auxiliary fiber material includes one or more of wood fiber, ramie fiber, and polypropylene fiber.

4. The preparation method according to claim 3, wherein, The auxiliary fiber is ramie fiber, and the mass ratio of the aromatic petroleum resin / basalt modified fiber composite material to ramie fiber is 5:2 to 1:

3.

5. The preparation method according to claim 1, wherein, The length of the aromatic petroleum resin / basalt modified fiber composite material is 5-20 mm; the length of the auxiliary fiber is 1.5-4 mm. The water-resistant sealing composite fiber material has a fiber diameter of 10-30 μm.

6. A water-resistant and sealing composite fiber material, which is obtained by the preparation method according to any one of claims 1-5.

7. A water-resistant sealing shield tail sealant, wherein the raw material of the water-resistant sealing shield tail sealant includes the water-resistant sealing composite fiber material as described in claim 6; in, Based on the total mass of the raw materials of the water-resistant sealing shield tail sealant being 100%, the raw materials of the water-resistant sealing shield tail sealant include: 15%-30% mixed base oil, 20%-35% thickener, 5%-15% adhesive, 5%-20% water-resistant sealing composite fiber material, 5%-10% water-absorbing and swelling material, and 3.2%-7.5% additives.

8. The water-resistant sealing shield tail sealant according to claim 7, wherein, The thickener includes one or more of the following: light calcium carbonate, light magnesium carbonate, heavy calcium carbonate, talc, mica powder, fumed silica, and kaolin. The adhesive includes one or more of the following: polyisobutylene, polymethyl methacrylate, coumarone resin, polyethylene, polypropylene, and ethylene-propylene copolymer. The water-absorbing and swelling material includes one or more of the following: high-sodium bentonite, sodium polyacrylate, carboxymethyl cellulose, polyvinyl alcohol, hydrophilic polyurethane prepolymer, acrylonitrile-vinyl acetate copolymer, polyvinyl alcohol and dipropylene ester crosslinker, and anionic polyacrylamide. The blended base oil includes one or more of the following: paraffinic base oil, intermediate base oil, naphthenic base oil, polyalphaolefin, alkylnaphthalene, trimethylolpropane ester, pentaerythritol ester, and dipentaerythritol ester.

9. The water-resistant sealing shield tail sealant according to claim 7 or 8, wherein, The thickener is composed of light calcium carbonate, organic bentonite, talc powder, mica powder and fumed silica; Based on the mass of light calcium carbonate, the content of organic bentonite is 0.5-5 times that of light calcium carbonate, the content of talc is 0.5-4 times that of light calcium carbonate, the content of mica powder is 0.2-1 times that of light calcium carbonate, and the content of fumed silica is 1-5 times that of light calcium carbonate.

10. The water-resistant sealing shield tail sealant according to claim 7 or 8, wherein, The adhesive is composed of polyisobutylene and ethylene-propylene copolymer; the mass ratio of polyisobutylene to ethylene-propylene copolymer is 2:1 to 1:

3.

11. The water-resistant sealing shield tail sealant according to claim 7 or 8, wherein, The water-absorbing and swelling material is composed of sodium polyacrylate and carboxymethyl cellulose; the mass ratio of sodium polyacrylate to carboxymethyl cellulose is 2:1 to 1:

2.

12. The water-resistant sealing shield tail sealant according to claim 7 or 8, wherein, The blended base oil consists of intermediate base oil MVI 150 and polyalphaolefin PAO 100; the mass ratio of intermediate base oil MVI 150 to polyalphaolefin PAO 100 is 3:1 to 1:

1.

13. The water-resistant sealing shield tail sealant according to claim 7, wherein, Based on the total mass of the raw materials of the water-resistant sealing shield tail sealant being 100%, the additives include: 1.5%-2.5% rust inhibitor, 1.5%-2.5% water-stabilizing chelating agent, and 0.2%-2.5% antioxidant.

14. The water-resistant sealing shield tail sealant according to claim 13, wherein, The rust inhibitor includes one or more of the following: benzimidazoles, sodium petroleum sulfonate, stearic acid, oleic acid, pentaerythritol monooleate, and sorbitan monooleate. The water-stabilized chelating agent includes one or more of sodium tripolyphosphate, sodium gluconate, ethylenediaminetetraacetic acid, tetrasodium ethylenediaminetetraacetic acid, ethylenediaminetetramethylenephosphonic acid, and diethylenetriaminepentamethylenephosphonic acid. The antioxidant includes one or more of 2',6-di-tert-butyl-p-cresol, octyl diphenylamine, and dipentyl dithiocarbamate.

15. The application of the water-resistant sealing grease for shield tail as described in any one of claims 7-14 in the field of shield tunneling construction.

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