A polyurethane grouting material and a method for producing the same

Abstract

This invention belongs to the technical field of functional materials for geotechnical engineering, specifically providing a polyurethane grouting material and its preparation method, comprising the following raw materials by mass percentage: 65%~80% polyol matrix, 3%~10% bifunctional rock reactive monomer, 2%~6% chain extender, 0.2%~1.5% catalyst, 4%~9% triethyl citrate, 0.5%~3% auxiliary agent, and the remainder being a composition of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate, with the sum of the mass percentages of the above components being 100%. This invention solves the problems of insufficient fluidity, reliance on physical bonding at the rock interface, poor stability, and insufficient durability in existing polyurethane grouting materials. This invention significantly improves water erosion resistance and long-term stability, significantly reduces the initial viscosity of the polyurethane grout, eliminates the need for small molecule diluents, avoids migration shrinkage and environmental risks, exhibits excellent storage stability, and is environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology for geotechnical engineering, specifically relating to a polyurethane grouting material and its preparation method. Background Technology

[0002] In tunnel engineering, slope reinforcement, and underground engineering, grouting technology is a key means to improve rock mass stability and seepage prevention. Polyurethane grouting fluids are widely used in geotechnical engineering due to their rapid curing and good bonding properties. However, existing polyurethane grouting fluids have the following technical problems: Insufficient fluidity: The fluidity of traditional polyurethane grouting materials is improved by physical means. Traditional formulations often add small molecule diluents such as isocyanates to reduce viscosity, but these substances are prone to migration and volatilization, leading to shrinkage of the cured body, generation of interfacial microcracks, and environmental health risks. Some solutions use low molecular weight polyols, which improve fluidity in the short term, but accelerate the gelation reaction and significantly shorten the pot life. Weak bonding with rocks: The interface between polyurethane and rocks mainly relies on physical bonding, with insufficient chemical bonding and poor long-term stability. Weak interfacial bonding mechanism: The surface of engineering rocks is rich in silanol, calcium and magnesium ions and carbonate active sites, while traditional polyurethane materials only adhere to the rock surface through physical action. Under the action of water erosion, freeze-thaw and dynamic load, the interface is prone to debonding failure. Although some studies have attempted to physically incorporate silane coupling agents into component B, there are three defects: (1) the amino groups in the coupling agent compete with the system catalyst or isocyanate for side reactions, consuming effective functional groups; (2) alkoxysilanes hydrolyze and condense prematurely when exposed to trace amounts of water during storage or mixing, forming gel particles and destroying the homogeneity of the slurry; (3) the coupling agent is randomly distributed in the polyurethane network and is difficult to migrate directionally to the slurry-rock interface, resulting in extremely low chemical bonding efficiency.

[0003] Insufficient durability: Polyurethane is prone to hydrolysis in humid environments, leading to a decline in performance.

[0004] The manufacturing process is disconnected from functional requirements: Current industrial processes generally employ a "room temperature simultaneous mixing" method, where polyols, catalysts, coupling agents, and other raw materials are added to a stirred tank and mixed uniformly to obtain the polymer. This process ignores the fact that the compound is prone to side reactions with trace amounts of water or hydroxyl components in the system in the presence of a catalyst, leading to a continuous increase in polymer viscosity over storage time. Furthermore, the consistently low-temperature operation fails to activate the directional reaction potential of specific functional groups, hindering the synergistic achievement of both high fluidity and interfacial chemical reaction objectives.

[0005] In summary, there is a pressing need in this field for a polyurethane grouting material that is innovative from the molecular design stage and matched with a refined preparation logic: it must be able to achieve spontaneous grout penetration into micron-level rock pores, and also be able to construct irreversible molecular-level connections at the polyurethane-rock interface through specific chemical reactions. Furthermore, the preparation process must ensure the stable embedding of functional components and prevent storage failure. Existing technologies have not yet provided a solution that meets these comprehensive requirements.

[0006] Chinese patent document CN118955854A discloses a mineral powder-reinforced polyurethane grouting material, its preparation method, and its application. The preparation method includes: S1, preparing a polyurethane prepolymer: under a nitrogen atmosphere, a polyurethane prepolymer is prepared using a polyol and an isocyanate; S2, preparing the mineral powder-reinforced polyurethane grouting material: after pretreatment, the polyurethane prepolymer is mixed with mineral powder until homogeneous; after further treatment, it is mixed with a curing agent and a crosslinking agent to obtain a urethane grouting material; the mass of mineral powder added is 10% to 40% of the mass of the urethane grouting material. The mineral powder-reinforced polyurethane grouting material prepared in this document is used for repairing cracks in asphalt pavements, but it cannot be widely applied in geotechnical engineering. Summary of the Invention

[0007] The present invention provides a polyurethane grouting material and its preparation method, aiming to overcome the problems of insufficient fluidity, reliance on physical bonding with rock interfaces, poor stability, and insufficient durability of existing polyurethane grouting materials.

[0008] Therefore, the present invention provides a polyurethane grouting material comprising the following raw materials in the following mass percentages: 65%~80% polyol matrix, 3%~10% bifunctional rock reactive monomer, 2%~6% chain extender, 0.2%~1.5% catalyst, 4%~9% triethyl citrate, 0.5%~3% auxiliary agent, and the remainder being a composition of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate, wherein the sum of the mass percentages of the above components is 100%.

[0009] Preferably, the polyol matrix is ​​a combination of low molecular weight polyols and high molecular weight polyols.

[0010] Preferably, the low molecular weight polyol is glycerol, and the high molecular weight polyol is polyoxypropylene glycol.

[0011] Preferably, the general molecular structural formula of the bifunctional rock reactive monomer is: (C2H5O)3Si—(CH2)3—NH—COO—(CH2)2—OP(O)(OC2H5)2.

[0012] Preferably, the chain extender is a combination of 1,4-butanediol and diethanolamine.

[0013] Preferably, the catalyst is a combination of dibutyltin dilaurate and N-ethylmorpholine.

[0014] Preferably, the auxiliary agent is a composition of polyether-modified siloxane defoamer, type 3A molecular sieve, and benzotriazole.

[0015] A method for preparing a polyurethane grouting material as described in any one of the claims, comprising the following steps: S1. Add the high molecular weight polyol in the polyol matrix (30%–50% of the formulation) and the bifunctional rock reaction monomer (the formulation amount) into the reactor. Heat the reactor to 60℃–75℃ under nitrogen protection and stir for 1–2 hours to obtain the prepolymer. S2. Cool the prepolymer to 35℃–40℃; S3. At 35℃–40℃, add the remaining amount of polyol matrix, chain extender, catalyst, triethyl citrate and auxiliary agent to the prepolymer, and stir for 20–35 minutes to obtain component B. S4. Mix component B with the formulated amount of the modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate compound evenly to complete the preparation.

[0016] Preferably, the constant temperature stirring reaction in step S1 requires maintaining a nitrogen atmosphere throughout, with an oxygen content of ≤10ppm in the nitrogen atmosphere.

[0017] Preferably, the prepolymer cooling rate in step S2 is 1–2 °C / min.

[0018] The beneficial effects of this invention are: The polyurethane grouting material and its preparation method of the present invention upgrade the bonding between the solidified body and the rock interface from physical adsorption to chemical bonding through bifunctional rock reactive monomers, significantly improving water erosion resistance and long-term stability. By using the raw materials formulated in the present invention and preparing the polyurethane grouting material according to the preparation method of the present invention, the initial viscosity of the polyurethane grout is significantly reduced, eliminating the need to add small molecule diluents, avoiding migration shrinkage and environmental risks, exhibiting excellent storage stability, and being environmentally friendly. Attached Figure Description

[0019] The present invention will now be described in further detail with reference to the accompanying drawings.

[0020] Figure 1 This is a flowchart of the preparation method for polyurethane grouting materials. Detailed Implementation

[0021] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0022] A polyurethane grouting material comprises the following raw materials in the following mass percentages: 65%~80% polyol matrix, 3%~10% bifunctional rock reactive monomer, 2%~6% chain extender, 0.2%~1.5% catalyst, 4%~9% triethyl citrate, 0.5%~3% auxiliary agent, and the remainder is a composition of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate, wherein the sum of the mass percentages of the above components is 100%.

[0023] The polyurethane grouting material of this invention upgrades the bonding between the solidified body and the rock interface from physical adsorption to chemical bonding through bifunctional rock reactive monomers, significantly improving water erosion resistance and long-term stability. Triethyl citrate is a high molecular weight environmentally friendly ester, avoiding the migration defects of traditional small molecule diluents. It works synergistically with bifunctional rock reactive monomers to maintain the low viscosity of the grout, significantly reducing the initial viscosity of the polyurethane grout. No small molecule diluents need to be added, avoiding migration shrinkage and environmental risks. It has excellent storage stability and is environmentally friendly.

[0024] This invention, through the rational selection and proportioning of raw materials, allows each raw material to work synergistically, resulting in a polyurethane grouting liquid with excellent initial viscosity, gelation time, compressive strength of the cured body, and bonding strength with granite. This significantly improves the durability of polyurethane grouting materials, providing an original solution for high-performance grouting materials. It is applicable to geotechnical engineering fields such as underground engineering, tunnels, and slope reinforcement.

[0025] Preferably, the polyol matrix is ​​a combination of low molecular weight polyols and high molecular weight polyols.

[0026] Specifically, polyurethane grouting materials are prepared by compounding low-molecular-weight polyols and high-molecular-weight polyols. The low-molecular-weight polyols enhance the strength, hardness, and early support of the cured material, while the high-molecular-weight polyols impart excellent toughness, elasticity, and resistance to deformation. At the same time, the viscosity of the system is effectively reduced, the fluidity and injectability are improved, and the uniformity of the cell or gel structure is optimized. Ultimately, the grouting material has good adhesion, impermeability, durability, and construction adaptability, making it suitable for different geological and engineering leak sealing and reinforcement needs.

[0027] Preferably, the low molecular weight polyol is glycerol, and the high molecular weight polyol is polyoxypropylene glycol.

[0028] Specifically, the trifunctionality of glycerol can be used to construct a high-density cross-linked network, which can significantly improve the strength, hardness, early support force and bonding and anchoring performance of the cured body. At the same time, the long-chain flexible structure of polypropylene glycol can give the material excellent elasticity, deformation resistance and fatigue resistance. The two work together to effectively reduce the viscosity of the system, optimize the fluidity and injectability of the grout, so that the grouting material has high strength, high elasticity, good impermeability, durability and construction adaptability, perfectly meeting the needs of engineering leakage plugging, seepage prevention and reinforcement scenarios.

[0029] Preferably, the general molecular structural formula of the bifunctional rock reactive monomer is: (C2H5O)3Si—(CH2)3—NH—COO—(CH2)2—OP(O)(OC2H5)2.

[0030] Specifically, the silane-phosphate dual-anchoring structure of the bifunctional rock reactive monomer enables the solidified body to form a network of Si-O-Si covalent bonds and metal coordination bonds with the rock. This upgrades the interfacial bonding from physical adsorption to chemical bonding, significantly improving water erosion resistance and long-term stability. The bifunctional rock reactive monomer acts as a molecular bridge chemically embedded in the polyurethane. Its dosage, verified through process testing, must be precisely matched to the system's isocyanate index (a combination of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate) to ensure interfacial enrichment without damaging the polyurethane matrix.

[0031] Preferably, the chain extender is a combination of 1,4-butanediol and diethanolamine.

[0032] Specifically, the chain extender composition of 1,4-butanediol and diethanolamine, in synergy with glycerol and polypropylene glycol, is used in the preparation of polyurethane grouting materials. 1,4-Butanediol provides a linear rigid chain extender structure, improving the tensile strength, modulus, and early crosslinking efficiency of the cured body. Diethanolamine, with its dual active sites of hydroxyl and amino groups, introduces flexible segments and enhances the reactivity and bonding properties of the system. The combination of the two can precisely control the crosslinking density, the ratio of soft and hard segments, and the microstructure of the polyurethane grouting material. While optimizing the grout viscosity and injectability, it endows the cured material with higher structural strength, excellent elastic recovery ability, good impermeability, and bonding and anchoring performance, further improving the comprehensive performance and durability of the material in engineering leak sealing and seepage prevention reinforcement scenarios.

[0033] Preferably, the catalyst is a combination of dibutyltin dilaurate and N-ethylmorpholine.

[0034] Specifically, the catalyst composition of dibutyltin dilaurate and N-ethylmorpholine, when applied to this polyurethane grouting material system, can synergistically regulate the reaction rate and gel equilibrium of polyurethane.

[0035] Preferably, the auxiliary agent is a composition of polyether-modified siloxane defoamer, type 3A molecular sieve, and benzotriazole.

[0036] Specifically, the auxiliary agent composition consisting of polyether-modified siloxane defoamer, 3A molecular sieve, and benzotriazole plays a synergistic role in this polyurethane grouting material system: the polyether-modified siloxane defoamer can quickly eliminate bubbles generated during raw material mixing and reaction, ensuring the uniformity of the grout and the density of the cured body, and avoiding the impact of pore defects on impermeability and mechanical properties; the 3A molecular sieve can efficiently adsorb trace amounts of moisture in the polyurethane grouting material system, preventing side reactions between water and the modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate to generate carbon dioxide, which would lead to foaming and bubbling problems, thus ensuring the stability of the material structure; benzotriazole can play a role in metal corrosion inhibition and antioxidant protection for the polyurethane grouting material system and the cured body, while improving the weather resistance and durability of the polyurethane grouting material. The combination of the three effectively optimizes the stability of the grout, the construction process, and the comprehensive performance of the final product, meeting the stringent requirements of engineering leak sealing and seepage prevention reinforcement.

[0037] like Figure 1 As shown, a method for preparing a polyurethane grouting material as described in any one of the claims includes the following steps: S1. Add the high molecular weight polyol in the polyol matrix (30%–50% of the formulation) and the bifunctional rock reaction monomer (the formulation amount) into the reactor. Heat the reactor to 60℃–75℃ under nitrogen protection and stir for 1–2 hours to obtain the prepolymer. S2. Cool the prepolymer to 35℃–40℃; S3. At 35℃–40℃, add the remaining amount of polyol matrix, chain extender, catalyst, triethyl citrate and auxiliary agent to the prepolymer, and stir for 20–35 minutes to obtain component B. S4. Mix component B with the formulated amount of the modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate compound evenly to complete the preparation.

[0038] This preparation method has the following technical advantages: Interfacial chemical bonding: The silane-phosphate dual anchoring structure of the bifunctional rock reactive monomer enables the solidified body to form a network of Si-O-Si covalent bonds and metal coordination bonds with the rock. The interfacial bonding is upgraded from physical adsorption to chemical bonding, which significantly improves water erosion resistance and long-term stability. Achieving high fluidity and harmlessness: Bifunctional rock reactive monomers are chemically embedded in polyurethane as molecular bridges. Through the molecular design and pre-embedding process of bifunctional rock reactive monomers, the initial viscosity of polyurethane grout is significantly reduced, eliminating the need to add small molecule diluents and avoiding migration shrinkage and environmental risks. Improved storage stability: Bifunctional rock reactive monomers are chemically embedded in polyurethane as molecular bridges, and the bifunctional rock reactive monomers are chemically bonded to the prepolymer. Their sensitive anchoring ends are effectively shielded. The viscosity change rate of component B is extremely low within 6 months of storage at room temperature, and the batch consistency is excellent. Enhancing environmental friendliness: The entire process uses environmentally friendly triethyl citrate and solvent-free technology, which is in line with the development trend of green building materials. Triethyl citrate is a high molecular weight environmentally friendly ester, which avoids the migration defects of traditional small molecule diluents and works synergistically with bifunctional rock reactive monomers to maintain the low viscosity of the slurry.

[0039] Preferably, the constant temperature stirring reaction in step S1 requires maintaining a nitrogen atmosphere throughout, with an oxygen content of ≤10ppm in the nitrogen atmosphere.

[0040] Preferably, the prepolymer cooling rate in step S2 is 1–2 °C / min.

[0041] Preferably, in step S4, the mass ratio of modified diphenylmethane diisocyanate to polymethylene polyphenyl polyisocyanate is 7:3; the preparation method of the compound of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate in step S4 is as follows: the modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate in a mass ratio of 7:3 are mixed and dehydrated at 45°C for 2 hours, cooled to 25°C and sealed for storage.

[0042] Preferably, the moisture content of component B is ≤0.05%.

[0043] Specifically, the moisture content in component B is ensured by a moisture scavenger to prevent premature hydrolysis of the anchoring end of the bifunctional rock reaction monomer.

[0044] Example 1: A polyurethane grouting material comprises the following raw materials in the following mass percentages: 72% polyol matrix (60% polypropylene glycol and 12% glycerol), 6% bifunctional rock reactive monomer, 4% chain extender (3% 1,4-butanediol and 1% diethanolamine), 0.8% catalyst (0.4% dibutyltin dilaurate and 0.4% N-ethylmorpholine), 7% triethyl citrate, 1.2% auxiliary agents (0.2% polyether-modified siloxane defoamer, 0.8% type 3A molecular sieve, and 0.2% benzotriazole), and the remainder is a composition of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate (the mass ratio of modified diphenylmethane diisocyanate to polymethylene polyphenyl polyisocyanate is 7:3), and the sum of the mass percentages of the above components is 100%.

[0045] A method for preparing the polyurethane grouting material includes the following steps: S1. Add the high molecular weight polyol (i.e., 28.8 parts of polyoxypropylene glycol) in the polyol matrix accounting for 40% of the formulation and 6 parts of bifunctional rock reaction monomer to a dried 500L stainless steel reactor. Purge the air in the reactor with high-purity nitrogen three times. The reactor has stirring, heating, cooling and heat preservation functions. Stir and heat the mixture in the reactor to 68°C and stir at a constant temperature for 1.5 hours to obtain the prepolymer. S2. Cool the prepolymer to 38°C, maintaining a slight positive pressure of nitrogen throughout the process; S3. At 38°C, add the remaining amount of polyol matrix (31.2 parts of polypropylene glycol and 12 parts of glycerol), 3 parts of 1,4-butanediol, 1 part of diethanolamine, 0.4 parts of dibutyltin dilaurate, 0.4 parts of N-ethylmorpholine, 7 parts of triethyl citrate, 0.2 parts of polyether-modified siloxane defoamer, 0.8 parts of type 3A molecular sieve, and 0.2 parts of benzotriazole to the prepolymer. Stir and mix for 28 minutes until the mixture is homogeneous and transparent to obtain component B. S4. Mix component B with 6.3 parts of the modified diphenylmethane diisocyanate and 2.7 parts of polymethylene polyphenyl polyisocyanate until homogeneous. Mix and dehydrate at 45°C for 2 hours, cool to 25°C and store in a sealed container to complete the preparation.

[0046] Example 2: A polyurethane grouting material comprises the following raw materials in the following mass percentages: 78% polyol matrix (63% polypropylene glycol and 15% glycerol), 4% bifunctional rock reactive monomer, 2.5% chain extender (2% 1,4-butanediol and 0.5% diethanolamine), 1.5% catalyst (0.5% dibutyltin dilaurate and 1.0% N-ethylmorpholine), 5% triethyl citrate, 0.8% auxiliary agents (0.2% polyether-modified siloxane defoamer, 0.5% type 3A molecular sieve, and 0.1% benzotriazole), and the remainder is a composition of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate (the mass ratio of modified diphenylmethane diisocyanate to polymethylene polyphenyl polyisocyanate is 7:3), and the sum of the mass percentages of the above components is 100%.

[0047] A method for preparing the polyurethane grouting material includes the following steps: S1. Add the high molecular weight polyol (i.e., 35.1 parts of polyoxypropylene glycol) in the polyol matrix accounting for 45% of the formulation and 4 parts of bifunctional rock reactive monomer to a dried 500L stainless steel reactor. Purge the air in the reactor with high-purity nitrogen three times. The reactor has stirring, heating, cooling and heat preservation functions. Stir and heat the mixture in the reactor to 70°C and stir at a constant temperature for 1.7 hours to obtain the prepolymer. S2. Cool the prepolymer to 39°C, maintaining a slight positive pressure of nitrogen throughout the process; S3. At 39°C, add the remaining amount of polyol matrix (27.9 parts of polypropylene glycol and 15 parts of glycerol), 2 parts of 1,4-butanediol, 0.5 parts of diethanolamine, 0.5 parts of dibutyltin dilaurate, 1 part of N-ethylmorpholine, 5 parts of triethyl citrate, 0.2 parts of polyether-modified siloxane defoamer, 0.5 parts of type 3A molecular sieve, and 0.1 parts of benzotriazole to the prepolymer. Stir and mix for 30 minutes until the mixture is homogeneous and transparent to obtain component B. S4. Mix component B with 5.74 parts of the modified diphenylmethane diisocyanate and 2.46 parts of polymethylene polyphenyl polyisocyanate until homogeneous. Mix and dehydrate at 47°C for 2.3 hours, cool to 25°C and store in a sealed container to complete the preparation.

[0048] Example 3: A polyurethane grouting material comprises the following raw materials by mass percentage: 68% polyol matrix (56% polypropylene glycol and 12% glycerol), 9% bifunctional rock reactive monomer, 5.5% chain extender (4% 1,4-butanediol and 1.5% diethanolamine), 1.2% catalyst (0.4% dibutyltin dilaurate and 0.8% N-ethylmorpholine), 7% triethyl citrate, 1.3% auxiliary agents (0.3% polyether-modified siloxane defoamer, 0.8% type 3A molecular sieve, and 0.2% benzotriazole), and the remainder is a composition of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate (the mass ratio of modified diphenylmethane diisocyanate to polymethylene polyphenyl polyisocyanate is 7:3), and the sum of the mass percentages of the above components is 100%.

[0049] A method for preparing the polyurethane grouting material includes the following steps: S1. Add the high molecular weight polyol (i.e., 23.8 parts of polyoxypropylene glycol) in the polyol matrix accounting for 35% of the formulation and 9 parts of bifunctional rock reactive monomer to a dried 500L stainless steel reactor. Purge the air in the reactor with high-purity nitrogen three times. The reactor has stirring, heating, cooling and heat preservation functions. Stir and heat the mixture in the reactor to 65°C and stir and react at a constant temperature for 1.3 hours to obtain the prepolymer. S2. Cool the prepolymer to 37°C, maintaining a slight positive pressure of nitrogen throughout the process; S3. At 37°C, add the remaining amount of polyol matrix (32.2 parts of polypropylene glycol and 12 parts of glycerol), 4 parts of 1,4-butanediol, 1.5 parts of diethanolamine, 0.4 parts of dibutyltin dilaurate, 0.8 parts of N-ethylmorpholine, 7 parts of triethyl citrate, 0.3 parts of polyether-modified siloxane defoamer, 0.8 parts of type 3A molecular sieve, and 0.2 parts of benzotriazole to the prepolymer. Stir and mix for 25 minutes until the mixture is homogeneous and transparent to obtain component B. S4. Mix component B with 5.74 parts of the compound of modified diphenylmethane diisocyanate and 2.46 parts of polymethylene polyphenyl polyisocyanate evenly, dehydrate at 43°C for 1.8 hours, cool to 25°C and store in a sealed container to complete the preparation.

[0050] Example 4: A polyurethane grouting material comprises the following raw materials in the following mass percentages: 65% polyol matrix (55% polypropylene glycol and 10% glycerol), 10% bifunctional rock reactive monomer, 6% chain extender (4% 1,4-butanediol and 2% diethanolamine), 1.5% catalyst (0.5% dibutyltin dilaurate and 1% N-ethylmorpholine), 9% triethyl citrate, 3% auxiliary agents (1% polyether-modified siloxane defoamer, 1.5% type 3A molecular sieve, and 0.5% benzotriazole), and the remainder is a composition of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate (the mass ratio of modified diphenylmethane diisocyanate to polymethylene polyphenyl polyisocyanate is 7:3), and the sum of the mass percentages of the above components is 100%.

[0051] A method for preparing the polyurethane grouting material includes the following steps: S1. Add the high molecular weight polyol (i.e., 19.5 parts of polyoxypropylene glycol) in the polyol matrix accounting for 30% of the formulation and 10 parts of bifunctional rock reactive monomer to a dried 500L stainless steel reactor. Purge the air in the reactor with high-purity nitrogen three times. The reactor has stirring, heating, cooling and heat preservation functions. Stir and heat the mixture in the reactor to 60°C and stir and react at a constant temperature for 1 hour to obtain the prepolymer. S2. Cool the prepolymer to 35°C, maintaining a slight positive pressure of nitrogen throughout the process; S3. At 35°C, add the remaining amount of polyol matrix (35.5 parts of polypropylene glycol and 10 parts of glycerol), 4 parts of 1,4-butanediol, 2 parts of diethanolamine, 0.5 parts of dibutyltin dilaurate, 1 part of N-ethylmorpholine, 9 parts of triethyl citrate, 1 part of polyether-modified siloxane defoamer, 1.5 parts of type 3A molecular sieve, and 0.5 parts of benzotriazole to the prepolymer. Stir and mix for 20 minutes until the mixture is homogeneous and transparent to obtain component B. S4. Mix component B with 3.85 parts of the compound of modified diphenylmethane diisocyanate and 1.65 parts of polymethylene polyphenyl polyisocyanate evenly, dehydrate at 40°C for 1.5 hours, cool to 25°C and store in a sealed container to complete the preparation.

[0052] Example 5: A polyurethane grouting material comprises the following raw materials in the following mass percentages: 80% polyol matrix (65% polypropylene glycol and 15% glycerol), 3% bifunctional rock reactive monomer, 2% chain extender (1.5% 1,4-butanediol and 0.5% diethanolamine), 0.2% catalyst (0.1% dibutyltin dilaurate and 0.1% N-ethylmorpholine), 4% triethyl citrate, 0.5% auxiliary agents (0.1% polyether-modified siloxane defoamer, 0.3% type 3A molecular sieve, and 0.1% benzotriazole), and the remainder is a composition of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate (the mass ratio of modified diphenylmethane diisocyanate to polymethylene polyphenyl polyisocyanate is 7:3), and the sum of the mass percentages of the above components is 100%.

[0053] A method for preparing the polyurethane grouting material includes the following steps: S1. Add 40 parts of high molecular weight polyol (i.e., polyoxypropylene glycol) and 3 parts of bifunctional rock reactive monomer from 50% of the polyol matrix to a dried 500L stainless steel reactor. Purge the air in the reactor with high-purity nitrogen three times. The reactor has stirring, heating, cooling and heat preservation functions. Stir and heat the mixture in the reactor to 75°C and stir at a constant temperature for 2 hours to obtain the prepolymer. S2. Cool the prepolymer to 40°C, maintaining a slight positive pressure of nitrogen throughout the process; S3. At 40°C, add the remaining amount of polyol matrix (25 parts of polypropylene glycol and 15 parts of glycerol), 1.5 parts of 1,4-butanediol, 0.5 parts of diethanolamine, 0.1 parts of dibutyltin dilaurate, 0.1 parts of N-ethylmorpholine, 4 parts of triethyl citrate, 0.1 parts of polyether-modified siloxane defoamer, 0.3 parts of type 3A molecular sieve, and 0.1 parts of benzotriazole to the prepolymer. Stir and mix for 35 minutes until the mixture is homogeneous and transparent to obtain component B. S4. Mix component B with 7.21 parts of the modified diphenylmethane diisocyanate and 3.09 parts of polymethylene polyphenyl polyisocyanate until homogeneous. Mix and dehydrate at 50°C for 2 hours, cool to 25°C and store in a sealed container to complete the preparation.

[0054] The defects of the traditional process are reproduced: If 6 parts of the bifunctional rock reaction monomer in Example 1 are directly added to the room temperature (23°C) mixing system (i.e., skipping steps S1 and S2, and mixing all raw materials simultaneously), the silane of the bifunctional rock reaction monomer reacts rapidly with trace water in the system during the stirring process to generate silanol and condense. Turbidity and microgel particles appear within 10 minutes, the viscosity of component B continues to increase, and it will be unusable after 24 hours.

[0055] The advantages of this invention are as follows: through the pre-reaction at 60–75℃ in step S1, the primary amino group of the bifunctional rock reactive monomer forms a stable chemical bond with the hydroxyl group of the polyol, fixing it at the end of the prepolymer chain. The steric hindrance and chemical environment of the silane and phosphate ester genes are changed, and they are in a dormant state. The low-temperature operation in steps S2 and S3 further inhibits its activity, ensuring that component B maintains low viscosity and chemical stability during storage.

[0056] The high-flowability polyurethane grouting liquids prepared in Examples 1-5 of this invention, which have chemical reactions with rocks, were compared with epoxy resin paste and traditional polyurethane grouting materials in terms of initial viscosity, gelation time, compressive strength of cured body, and bond strength with granite. The test results are shown in Table 1. Table 1. Comparison of performance indicators of high-flowability polyurethane grouting fluids with chemical reaction with rocks prepared in Examples 1-5, traditional grouting materials, and epoxy resin grouting materials.

[0057] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. All designs that are the same as or similar to the present invention are within the scope of protection of the present invention.

Claims

1. A polyurethane grouting material, characterized in that: The raw materials include the following mass percentages: 65%~80% polyol matrix, 3%~10% bifunctional rock reaction monomer, 2%~6% chain extender, 0.2%~1.5% catalyst, 4%~9% triethyl citrate, 0.5%~3% auxiliary agent, and the remainder is a composition of modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate, and the sum of the mass percentages of the above components is 100%.

2. The polyurethane grouting material as described in claim 1, characterized in that: The polyol matrix is ​​a combination of low molecular weight polyols and high molecular weight polyols.

3. The polyurethane grouting material as described in claim 2, characterized in that: The low molecular weight polyol is glycerol, and the high molecular weight polyol is polyoxypropylene glycol.

4. The polyurethane grouting material as described in claim 1, characterized in that: The general molecular structural formula of the bifunctional rock reactive monomer is: (C2H5O)3Si—(CH2)3—NH—COO—(CH2)2—OP(O)(OC2H5)2.

5. The polyurethane grouting material as described in claim 1, characterized in that: The chain extender is a combination of 1,4-butanediol and diethanolamine.

6. The polyurethane grouting material as described in claim 1, characterized in that: The catalyst is a combination of dibutyltin dilaurate and N-ethylmorpholine.

7. The polyurethane grouting material as described in claim 1, characterized in that: The auxiliary agent is a combination of polyether-modified siloxane defoamer, type 3A molecular sieve, and benzotriazole.

8. A method for preparing a polyurethane grouting material as described in any one of claims 1-7, characterized in that: Includes the following steps: S1. Add the high molecular weight polyol in the polyol matrix (30%–50% of the formulation) and the bifunctional rock reaction monomer (the formulation amount) into the reactor. Heat the reactor to 60℃–75℃ under nitrogen protection and stir for 1–2 hours to obtain the prepolymer. S2. Cool the prepolymer to 35℃–40℃; S3. At 35℃–40℃, add the remaining amount of polyol matrix, chain extender, catalyst, triethyl citrate and auxiliary agent to the prepolymer, and stir for 20–35 minutes to obtain component B. S4. Mix component B with the formulated amount of the modified diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate compound evenly to complete the preparation.

9. The method for preparing the polyurethane grouting material as described in claim 8, characterized in that: The constant temperature stirring reaction in step S1 requires maintaining a nitrogen atmosphere throughout, with an oxygen content of ≤10ppm.

10. The method for preparing the polyurethane grouting material as described in claim 8, characterized in that: The cooling rate of the prepolymer in step S2 is 1–2 °C / min.

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