Shrinkage-free single-component polyurethane grouting material and preparation method thereof

Abstract

The invention relates to the technical field of building waterproof materials, and particularly discloses a shrinkage-free single-component polyurethane grouting material and a preparation method thereof. The shrinkage-free single-component polyurethane grouting material provided by the invention is prepared from the following raw material components: polyether polyol, isocyanate, a plasticizer, a catalyst, a surfactant, a flame retardant, a hydrophilic agent, a foam stabilizer and a whisker-fiber complex. Isocyanate and polyether polyol react to generate a prepolymer, meanwhile, residual isocyanate monomers react to generate carbon dioxide, a closed-cell or open-cell foam structure is formed in the grouting material in cooperation with a foam homogenizing agent, and volume shrinkage generated in the cross-linking and curing process of polymer chain segments is effectively counteracted; meanwhile, the whisker-fiber complex constructs a three-dimensional continuous rigid supporting framework in a matrix, and the expansion microspheres capable of absorbing escape water are matched, so that the effect that the volume of a grouting material solidified body is not shrunk after water loss is truly achieved.

Description

Technical Field

[0001] This application belongs to the field of building materials technology, and in particular relates to a non-shrinkage single-component polyurethane grout and its preparation method. Background Technology

[0002] Polyurethane grout, as a core material for modern building structure reinforcement, is widely used in civil engineering and underground space development due to its rapid penetration, elastic consolidation, and environmental friendliness. Its core component, the prepolymer, is produced by reacting polyether polyol with isocyanate; it rapidly forms an elastic consolidation upon contact with water, exhibiting both aging resistance and concrete adhesion properties. However, with the increasing complexity of engineering environments, the requirements for the shrinkage performance of grout are becoming increasingly stringent.

[0003] Patent CN114163808A discloses a flame-retardant, low-shrinkage, hydrophobic polyurethane grouting composition. It adopts a synergistic system of compounded polyether polyol and flame retardant to indirectly reduce shrinkage by improving the safety of the solidified body. However, the solidified body of this technology still has volume shrinkage after water loss. In addition, due to the large amount of inert solvent used in polyurethane grouting materials, the shrinkage problem after the solidified body dries is more prominent, which can easily lead to secondary leakage.

[0004] While traditional low-shrinkage technologies can partially mitigate volume changes, under structural deformation conditions, the solidified body still experiences significant shrinkage due to water loss or stress concentration, leading to a persistently high risk of re-leakage. Therefore, developing a truly zero-shrinkage, single-component polyurethane grout has become a critical technological bottleneck that the industry urgently needs to overcome. Summary of the Invention

[0005] This application improves a non-shrinkage single-component polyurethane grout and its preparation method, which has the effect of improving the volume shrinkage that occurs after the solidified body loses water.

[0006] Firstly, the non-shrink, single-component polyurethane grouting material provided in this application adopts the following technical solution: A non-shrink, one-component polyurethane grouting material comprises the following raw material components in parts by weight: 90-110 parts polyether polyol, 20-40 parts isocyanate, 5-10 parts plasticizer, 0-5 parts catalyst, 2-3 parts surfactant, 5-10 parts flame retardant, 1-2 parts hydrophilic agent, and 1-5 parts foam leveling agent; wherein the polyether polyol is one or more of polyether diol, polyether triol, and polyether tetraol; the isocyanate is one or more of isophorone diisocyanate, polymethylene polyphenyl isocyanate, and diphenylmethane diisocyanate; and the foam leveling agent is one or more of L-6900 and L-838.

[0007] Through the above technical solution, the molecular chain of polyether polyol contains ether bonds and hydroxyl groups. These polar groups react with isocyanate to form a three-dimensional cross-linked network. By adjusting the molecular weight and hydroxyl value of polyether polyol, the cross-linking density can be controlled and shrinkage stress reduced. Meanwhile, the moisture in the air reacts with the small amount of residual isocyanate monomer in the system to produce carbon dioxide. The low total amount of isocyanate limits the amount of carbon dioxide produced, but it is enough to form a uniform, fine closed-cell or open-cell foam structure inside the grout. During the formation and expansion of these bubbles, they effectively offset the volume shrinkage caused by the increased intermolecular forces and tight chain arrangement of polymer segments during the cross-linking and curing process. This plays a key role in achieving zero shrinkage in the grout, and together with other raw material components, it achieves true zero shrinkage in the grout.

[0008] Polyether diols impart excellent flexibility and elastic recovery to the cured product; polyether triols and tetraols introduce branching points and higher functionality, significantly increasing crosslinking density. Highly crosslinked networks enhance the binding forces between molecular chains, reducing inherent shrinkage caused by chain rearrangement and tight packing during curing; and improve the strength and rigidity of the cell walls, making the carbon dioxide bubbles generated during foaming more stable, resisting compression and collapse, thus more effectively maintaining the expansion volume. By adjusting the proportions of polyols with different functionalities, the flexibility, strength, modulus, and crosslinking density of the system can be precisely balanced.

[0009] Isophorone diisocyanate is characterized by low reactivity and enhanced weather resistance; diphenylmethane diisocyanate is characterized by high reactivity and high strength; polymethylene polyphenyl isocyanate is characterized by high functional groups and high viscosity. By selecting or combining IPDI, MDI, and PAPI individually, the viscosity, curing speed, final hardness, flexibility, and other properties of the prepolymer can be optimized to adapt to different construction conditions and performance requirements.

[0010] The foam leveling agent precisely controls the foaming of carbon dioxide, forming a uniform, stable, and dense microporous foam structure. The siloxane segments of L-6900 reduce surface tension and increase the reaction rate, while the reactive silane groups of L-838 can covalently bond with isocyanates, constructing a reinforcing network on the cell walls. The foam leveling agent can be selected based on the performance of the grouting material, or a synergistic effect can be achieved through the combination of different foam leveling agents.

[0011] Optionally, the polyether polyol has a molecular weight of 3000-50000 and a hydroxyl value of 15-55 mgKOH / g.

[0012] Through the above technical solution, the long-chain flexibility of high molecular weight polyether polyol combined with a highly cross-linked network gives the grout internal structure anti-collapse toughness, maintaining the initial volume after grouting. The high hydroxyl value of polyether polyol provides more hard segment links, which helps to improve the strength after grouting.

[0013] Optionally, the plasticizer is one or more of dibutyl phthalate and dioctyl phthalate.

[0014] Through the above technical solutions, the rigid benzene ring structure of dibutyl phthalate or dioctyl phthalate plasticizer provides a molecular-level support skeleton for the polyurethane network to resist shrinkage stress, and its flexible ester chain can penetrate the polyether network to reduce the viscosity of the system and ensure the fluidity of the grout during construction.

[0015] Optionally, the flame retardant is one or more of TCPP, TCEP, TDCPP, and DMMP.

[0016] Through the above technical solutions, each flame retardant has its own characteristics. TCPP provides high flame retardant efficiency due to the chlorine-phosphorus synergistic effect; TCEP enhances the system's permeability with its low molecular weight; TDCPP contributes excellent thermal stability and durability; while DMMP achieves high-efficiency flame retardancy with low addition amount due to its ultra-high phosphorus content. Different flame retardants with different properties can be selected according to the grouting material, or functional synergy can be achieved through the compounding of different flame retardants.

[0017] Optionally, the surfactant is one or more of lauric acid and Tween-80.

[0018] Through the above technical solutions, lauric acid can construct a rigid foam skeleton to resist shrinkage stress through carboxyl group reaction; Tween-80, with its polyoxyethylene chain-enhanced moisture dispersion, ensures uniform foaming throughout the entire surface. Surfactants can be selected based on the performance of the grouting material, or functional synergy can be achieved through the compounding of different surfactants.

[0019] Optionally, the catalyst is one or more of the following: stannous octoate, dibutyltin dilaurate, stannous octoate, triethylene alcoholamine, triethanolamine, bis(2-morpholinodiethyl) ether, and N,N,N',N'-tetramethyldipropylenetriamine.

[0020] The above technical solution allows for precise control of the prepolymer gelation time by selecting or combining individual catalysts.

[0021] Optionally, the hydrophilic agent is dimethyl sulfoxide.

[0022] Through the above technical solution, dimethyl sulfoxide, as a hydrophilic agent, can reduce the obstruction of water diffusion due to its strong polarity and hydrogen bond breaking ability, thereby achieving rapid wetting of the grout.

[0023] Optionally, the raw material components further include 0-5 parts of whisker-fiber composite, and the preparation method of the whisker-fiber composite includes the following steps: S1, Whisker-fiber blending: Calcium sulfate whiskers and chopped glass fibers are added to a high-speed mixer at a mass ratio of 4-5:1, and 0.4-0.5wt% KH-570 is added and mixed for 15-30 minutes. S2. Preparation of epoxy-modified polyurethane prepolymer: S21. Add isophorone diisocyanate and polyether diol in a mass ratio of 1:2-3 to the reactor and heat to 80-90℃, then add 0.1-0.2wt% dibutyltin dilaurate and react for 2-3 hours. S22. After the reaction of the S21 mixture is completed, lower the temperature to 65-75℃, add 15-18wt% glycidol dropwise, and react at 65-75℃ for 2-3 hours. S3, Surface isocyanate treatment: The mixture obtained in S1 is placed in a fluidized bed and sprayed with an atomized acetone solution containing 5-6 wt% epoxy-modified polyurethane prepolymer. The temperature is controlled at 60-70℃ and the reaction is carried out for 45-60 minutes. S4, Expanded Microsphere Linkage: The S3 mixture with a mass ratio of 6-7:1 and the expanded microspheres are placed in a vacuum drum reactor and reacted at 40-50℃ for 1.5-2 hours. After the reaction is completed, the mixture is vacuum dried at 40-50℃ for 6-7 hours to obtain the whisker-fiber composite.

[0024] Through the above technical solution, the mixed weaving and modification of calcium sulfate whiskers and glass fibers, with the surface of the composite grafted with a silane coupling agent to form hydrophilic groups, achieves low sedimentation and uniform dispersion in the grout, and constructs a three-dimensional continuous rigid support framework within the matrix. This framework, through the high modulus characteristics of the whiskers and the bridging effect of the fibers, continuously provides stress-resistant support during the curing and application stages, effectively resisting the risk of volume collapse caused by shrinkage and maintaining the structural integrity of the grout cavity areas.

[0025] Furthermore, an active isocyanate group is directionally introduced onto the surface of the composite through a fluidized bed isocyanate process. These groups undergo a covalent bonding reaction with the polyurethane prepolymer with hydroxyl-terminated ends, improving the compatibility between the supporting skeleton and the polymer matrix, eliminating the weak bonds caused by traditional physical mixing, and ensuring the effective transfer of support force from the skeleton to the entire grouting material.

[0026] Through an epoxy-isocyanate reaction, the expanded microspheres are chemically bonded to the three-dimensional framework of whiskers and fibers. This allows the microspheres to precisely capture water escaping from the grouting cavity, and upon contact with water, they expand to offset the volume shrinkage of the water-loss areas, forming a "shrinkage-expansion" equilibrium system.

[0027] Optionally, the method for preparing the expanded microspheres includes the following steps: S1, Kernel Synthesis: S11. Dissolve acrylic acid and acrylamide in water at a molar ratio of 7-8:3, add 0.4-0.5 wt% methylenebisacrylamide, and heat to 65-75℃ under nitrogen protection. S12. Add 0.2-0.3wt% potassium persulfate solution dropwise, react for 3-4 hours, then centrifuge and wash. After centrifugation, vacuum dry at 40-50℃ for 3-4 hours. After drying, pulverize and sieve. S2, Microsphere Packaging: S21. Disperse the powder obtained in S1 in acetone, add 4-5wt% KH-550 and sonicate for 30min. S22. After ultrasonication, simultaneously add 8-10 wt% acetone solution containing HDI type prepolymer and 0.1-0.2 wt% dibutyltin dilaurate catalyst, react at 40-50℃ for 2 hours, centrifuge after reaction, and vacuum dry at 50-60℃ for 4 hours after centrifugation. S3, Surface epoxy functionalization: The solid obtained in S2 is dispersed in an acetone solution containing 3-5 wt% epichlorohydrin, refluxed at 60-70℃ for 3-4 hours, centrifuged and washed after reflux, and vacuum dried at 50℃ for 4 hours to obtain expanded microspheres.

[0028] The above technical solution constructs a highly absorbent resin core driven by ionic osmotic pressure through the crosslinking polymerization of acrylic acid and acrylamide. Under the crosslinking control of methylenebisacrylamide, this core expands in volume upon contact with water, contributing to resistance to shrinkage.

[0029] Furthermore, a polyurethane shell is constructed on the surface of the resin core to stabilize the expansion coefficient of the microspheres, avoid excessive expansion stress from damaging the grout matrix, and at the same time, the shell blocks the penetration of other components in the grout, ensuring that the microspheres are activated only in the dehydrated area.

[0030] By modifying the surface of epichlorohydrin, high-density epoxy groups are introduced into the shell of the microspheres. These active groups form chemical bonds with the whiskers-fibers and, relying on the whisker-fiber network, achieve uniform distribution of the microspheres inside the grout. When local water escapes, the anchored expanding microspheres precisely expand to fill the gaps, offsetting the volume shrinkage caused by water loss.

[0031] Secondly, this application provides a method for preparing a non-shrink, one-component polyurethane grout, employing the following technical solution: A method for preparing a non-shrink, one-component polyurethane grout includes the following steps: S1. Add the polyether polyol to the reactor and stir and dehydrate for 2-3 hours under vacuum at 90-130℃. S2. Reduce the temperature of the reactor from S1 to 65-75℃, add isocyanate under nitrogen protection, and react at 65-75℃ for 1.5h. S3. Reduce the temperature of the S2 reactor to 50-60℃, add plasticizer, catalyst, surfactant, flame retardant, hydrophilic agent, foam stabilizer, and whisker-fiber composite, and stir under nitrogen protection for 0.5-1h to obtain a non-shrinkage single-component waterborne polyurethane grouting material.

[0032] The above technical solution involves: firstly, deep dehydration of polyether polyol in a high-temperature vacuum environment to block the pre-reaction of isocyanate, and then synthesizing prepolymer under nitrogen protection. In the further low-temperature compounding stage, whisker-fiber composite is preferentially added to form a pre-bonded interface, simultaneously protecting the integrity of the expanded microspheres, and allowing flame retardants and other fillers to be uniformly dispersed through the fiber mesh, thus obtaining a non-shrinkage single-component polyurethane grout.

[0033] In summary, this application includes at least one of the following beneficial technical effects: 1. A prepolymer is generated by reacting isocyanate with polyether polyol. At the same time, the residual isocyanate monomer reacts to generate carbon dioxide, which, together with a foam leveling agent, forms a uniform and fine closed-cell or open-cell foam structure inside the grout. During the formation and expansion of these bubbles, the volume shrinkage caused by the increased intermolecular forces and tight chain arrangement of polymer segments during cross-linking and curing is effectively offset. This plays a key role in achieving zero shrinkage in the grout, and together with other raw material components, it achieves true zero shrinkage in the grout.

[0034] 2. By incorporating whisker-fiber composites into the grout raw material components, a three-dimensional continuous rigid support framework is constructed within the matrix, continuously providing stress resistance during the curing and application stages. This effectively resists the risk of volume collapse caused by shrinkage and maintains the structural integrity of the grout cavity areas. Furthermore, the synergistic effect of expandable microspheres linked to the whiskers-fibers ensures that when local moisture escapes, the linked microspheres precisely expand to fill the voids, offsetting the volume shrinkage caused by water loss. Detailed Implementation

[0035] The present application will be further described in detail below with reference to the embodiments.

[0036] In this specific embodiment, there are no other special circumstances, and the components used are as follows: Polyether polyols: 330N, GJ-48; Isocyanates: TDI-80, IPDI; Plasticizer: DOP; Foaming agents: L-6900, L-838; Catalysts: T12, triethanolamine; Surfactant: Tween-80; Flame retardant: TCPP; Hydrophilic agent: dimethyl sulfoxide.

[0037] Preparation Example 1 The preparation method of expanded microspheres includes the following steps: S1, Kernel Synthesis: S11. Dissolve acrylic acid and acrylamide in water at a molar ratio of 7:3, add 0.5 wt% methylenebisacrylamide, and heat to 65°C under nitrogen protection. S12. Add 0.3wt% potassium persulfate solution, react for 3 hours, centrifuge and wash, dry under vacuum at 50℃ for 4 hours after centrifugation, and then pulverize and sieve after drying. S2, Microsphere Packaging: S21. Disperse the powder obtained in S1 in acetone, add 5wt% KH-550 and sonicate for 30min. S22. After ultrasonication, 10wt% acetone solution containing HDI type prepolymer and 0.1wt% dibutyltin dilaurate catalyst were added dropwise. The reaction was carried out at 40℃ for 2h. After the reaction was completed, the mixture was centrifuged and then vacuum dried at 50℃ for 4h. S3, Surface epoxy functionalization: The solid obtained in S2 is dispersed in an acetone solution containing 5 wt% epichlorohydrin, refluxed at 60°C for 4 hours, centrifuged and washed after reflux, and vacuum dried at 50°C for 4 hours to obtain expanded microspheres.

[0038] Preparation Example 2 The preparation method of expanded microspheres includes the following steps: S1, Kernel Synthesis: S11. Dissolve acrylic acid and acrylamide in water at a molar ratio of 7:3, add 0.5 wt% methylenebisacrylamide, and heat to 65°C under nitrogen protection. S12. Add 0.3wt% potassium persulfate solution, react for 3 hours, centrifuge and wash, dry under vacuum at 50℃ for 4 hours after centrifugation, and then pulverize and sieve after drying. S2, Microsphere Packaging: S21. Disperse the powder obtained in S1 in acetone, add 5wt% KH-550 and sonicate for 30min. S22. After ultrasonication, 10wt% acetone solution containing HDI type prepolymer and 0.1wt% dibutyltin dilaurate catalyst were added dropwise. The reaction was carried out at 40℃ for 2h. After the reaction was completed, the mixture was centrifuged and then vacuum dried at 50℃ for 4h.

[0039] Preparation Example 3 The preparation method of whisker-fiber composite includes the following steps: S1, Whisker-fiber blending: Calcium sulfate whiskers and chopped glass fibers are added to a high-speed mixer at a mass ratio of 8:2, and 0.5wt% KH-570 is added and mixed for 15min; S2. Preparation of epoxy-modified polyurethane prepolymer: S21. Add isophorone diisocyanate and polyether diol in a mass ratio of 1:2 to the reactor and heat to 80°C. Then add 0.1wt% dibutyltin dilaurate and react for 2 hours. S22. After the reaction of the S21 mixture is completed, the temperature is lowered to 75°C, and 18wt% glycidol is added dropwise. The mixture is then reacted at 75°C for 3 hours. S3, Surface isocyanate treatment: The mixture obtained in S1 is placed in a fluidized bed and sprayed with an atomized acetone solution containing 6 wt% epoxy-modified polyurethane prepolymer. The reaction is carried out at 70°C for 45 minutes. S4, Expanded Microsphere Linkage: The S3 mixture with a mass ratio of 6:1 and the expanded microspheres were placed in a vacuum drum reactor and reacted at 45°C for 1.5 h. After the reaction was completed, the mixture was vacuum dried at 40°C for 6 h to obtain the whisker-fiber composite.

[0040] Specifically, the expanded microspheres used were those prepared in Preparation Example 1.

[0041] Preparation Example 4 The difference between this preparation example and preparation example 3 is that the expanded microspheres are replaced with an equal amount of the expanded microspheres prepared in preparation example 2.

[0042] Preparation Example 5 The preparation method of whisker-fiber composite includes the following specific steps: S1, Whisker-fiber blending: Calcium sulfate whiskers and chopped glass fibers are added to a high-speed mixer at a mass ratio of 8:2, and 0.5wt% KH-570 is added and mixed for 15min; S2. Preparation of epoxy-modified polyurethane prepolymer: S21. Add isophorone diisocyanate and polyether diol in a mass ratio of 1:2 to the reactor and heat to 80°C. Then add 0.1wt% dibutyltin dilaurate and react for 2 hours. S22. After the reaction of the S21 mixture is completed, the temperature is lowered to 75°C, and 18wt% glycidol is added dropwise. The mixture is then reacted at 75°C for 3 hours. S3, Surface isocyanate esterification: The mixture obtained in S1 is placed in a fluidized bed and sprayed with an atomized acetone solution containing 6 wt% epoxy-modified polyurethane prepolymer. The reaction is carried out at 70°C for 45 minutes. After the reaction is completed, it is vacuum dried at 40°C for 6 hours.

[0043] Preparation Example 6 The preparation method of whisker-fiber composite includes the following specific steps: S1, Whisker-fiber blending: Calcium sulfate whiskers and chopped glass fibers are added to a high-speed mixer at a mass ratio of 8:2, and 0.5wt% KH-570 is added and mixed for 15min; S2, Expanded Microsphere Linkage: The S1 mixture with a mass ratio of 6:1 and expanded microspheres were placed in a vacuum drum reactor and reacted at 45°C for 1.5 h. After the reaction was completed, the mixture was vacuum dried at 40°C for 6 h to obtain a whisker-fiber composite.

[0044] Specifically, the expanded microspheres used were those prepared in Preparation Example 1.

[0045] Example 1 A non-shrink, one-component polyurethane grouting material comprises the following raw materials in parts by weight: 100 parts of polyether polyol (330N), 20 parts of isocyanate (TDI-80), 10 parts of isocyanate (IPDI), 5 parts of plasticizer, 5 parts of foam leveling agent (L-6900), 1 part of catalyst (T12), 2 parts of catalyst (triethanolamine), 2 parts of surfactant, 5 parts of flame retardant, 1 part of hydrophilic agent, and 3 parts of whisker-fiber composite.

[0046] Specifically, the whisker-fiber composite used is the whisker-fiber composite prepared in Preparation Example 3.

[0047] The preparation method of non-shrink one-component polyurethane grout includes the following specific steps: S1. Add the polyether polyol to the reactor and stir to dehydrate for 3 hours under vacuum at 120°C. S2. Reduce the temperature of the reactor from S1 to 65°C, add isocyanate under nitrogen protection, and react at 65°C for 1.5 hours. S3. Reduce the temperature of the S2 reactor to 50°C, add plasticizer, catalyst, surfactant, flame retardant, hydrophilic agent, foam stabilizer, and whisker-fiber composite, and stir for 0.5 h under nitrogen protection to obtain a non-shrinkage single-component waterborne polyurethane grouting material.

[0048] Example 2 A non-shrinkage, one-component polyurethane grouting material comprises the following raw materials in parts by weight: 100 parts of polyether polyol (GJ-48), 20 parts of isocyanate (TDI-80), 10 parts of isocyanate (IPDI), 5 parts of plasticizer, 5 parts of foam leveling agent (L-838), 1 part of catalyst (T12), 2 parts of catalyst (triethanolamine), 2 parts of surfactant, 5 parts of flame retardant, 1 part of hydrophilic agent, and 3 parts of whisker-fiber composite.

[0049] Specifically, the whisker-fiber composite used is the whisker-fiber composite prepared in Preparation Example 3.

[0050] Example 3 A non-shrinkage, one-component polyurethane grouting material comprises the following raw materials in parts by weight: 50 parts of polyether polyol (330N), 50 parts of polyether polyol (GJ-48), 20 parts of isocyanate (TDI-80), 10 parts of isocyanate (IPDI), 5 parts of plasticizer, 5 parts of foam leveling agent (L-838), 1 part of catalyst (T12), 2 parts of catalyst (triethanolamine), 2 parts of surfactant, 5 parts of flame retardant, 1 part of hydrophilic agent, and 3 parts of whisker-fiber composite.

[0051] Specifically, the whisker-fiber composite used is the whisker-fiber composite prepared in Preparation Example 3.

[0052] Example 4 The difference between this embodiment and Example 1 is that the whisker-fiber composite is replaced with an equal amount of the whisker-fiber composite prepared in Example 4.

[0053] Example 5 The difference between this embodiment and Example 1 is that the whisker-fiber composite is replaced with an equal amount of the whisker-fiber composite prepared in Example 5.

[0054] Example 6 The difference between this embodiment and Example 1 is that the whisker-fiber composite is replaced with an equal amount of the whisker-fiber composite prepared in Example 6.

[0055] Example 7 The difference between this embodiment and Example 1 is that the whisker-fiber composite is replaced with an equal amount of the expanded microspheres prepared in Example 1.

[0056] Detection example According to the performance data of the grouting material tested in JC / T2041-2020 "Polyurethane Grouting Materials", The test results are shown in Table 1.

[0057] Table 1 As can be seen from the performance data tables of Examples 1-7, the grouting material prepared in this application has significantly improved in terms of gel time, water-binding properties, viscosity, foaming rate, and water swelling rate. In particular, it achieves true zero shrinkage in terms of volume shrinkage rate, solving the problem of water loss and volume shrinkage of the grouting material solidified body.

[0058] The performance test data from Examples 1-3 show that the types of polyether polyols and foam levelers have a significant impact on the performance of the grouting material. Adjusting the type of polyether polyol and foam leveler significantly improves the performance of the grouting material. The reaction between polyether polyol and isocyanate generates a prepolymer, which, combined with the foam leveler, forms a uniform, fine closed-cell or open-cell foam structure within the grouting material. This effectively counteracts the volume shrinkage caused by increased intermolecular forces and tighter chain arrangement during the cross-linking and curing process of the polymer chains, playing a crucial role in achieving shrinkage-free grouting.

[0059] As can be seen from the performance test data tables of Examples 1, 6 and 7, the whisker-fiber composite constructs a three-dimensional support network by uniformly distributing the highly dispersed whiskers-fibers within the grout, and, in conjunction with the expansion mechanism of the expanded microspheres, resists the volume shrinkage caused by water loss in the grout, ensuring that the grout achieves true shrinkage-free performance.

[0060] As can be seen from the performance test data tables of Examples 1, 4 and 5, the expanded microspheres are attached to the whiskers-fibers and are evenly distributed inside the grout. They absorb the water that escapes from the grout and offset the volume shrinkage caused by water loss through expansion, thus achieving a smart response of local water loss offsetting.

[0061] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A non-shrink, one-component polyurethane grout, characterized in that, The raw material components include the following parts by weight: 90-110 parts polyether polyol, 20-40 parts isocyanate, 5-10 parts plasticizer, 0-5 parts catalyst, 2-3 parts surfactant, 5-10 parts flame retardant, 1-2 parts hydrophilic agent, and 1-5 parts foam stabilizer; wherein the polyether polyol is one or more of polyether diol, polyether triol, and polyether tetraol; wherein the isocyanate is one or more of isophorone diisocyanate, polymethylene polyphenyl isocyanate, and diphenylmethane diisocyanate; and wherein the foam stabilizer is one or more of L-6900 and L-838.

2. The non-shrink, single-component polyurethane grouting material according to claim 1, characterized in that: The polyether polyol has a molecular weight of 3000-50000 and a hydroxyl value of 15-55 mg KOH / g.

3. The non-shrink, single-component polyurethane grouting material according to claim 1, characterized in that: The plasticizer is one or more of dibutyl phthalate and dioctyl phthalate.

4. The non-shrink, single-component polyurethane grouting material according to claim 1, characterized in that: The flame retardant is one or more of TCPP, TCEP, TDCPP, and DMMP.

5. The non-shrink, single-component polyurethane grouting material according to claim 1, characterized in that: The surfactant is one or more of lauric acid and Tween-80.

6. The non-shrink, single-component polyurethane grouting material according to claim 1, characterized in that: The catalyst is one or more of the following: stannous octoate, dibutyltin dilaurate, stannous octoate, triethylene alcoholamine, triethanolamine, bis(2-morpholinodiethyl) ether, and N,N,N',N'-tetramethyldipropylenetriamine.

7. The non-shrink, single-component polyurethane grouting material according to claim 1, characterized in that: The hydrophilic agent is dimethyl sulfoxide.

8. The non-shrink, single-component polyurethane grouting material according to claim 1, characterized in that: The raw material components also include 0-5 parts of whisker-fiber composite, and the preparation method of the whisker-fiber composite includes the following steps: S1, Whisker-fiber blending: Calcium sulfate whiskers and chopped glass fibers are added to a high-speed mixer at a mass ratio of 4-5:1, and 0.4-0.5wt% KH-570 is added and mixed for 15-30 minutes. S2. Preparation of epoxy-modified polyurethane prepolymer: S21. Add isophorone diisocyanate and polyether diol in a mass ratio of 1:2-3 to the reactor and heat to 80-90℃, then add 0.1-0.2wt% dibutyltin dilaurate and react for 2-3 hours. S22. After the reaction of the S21 mixture is completed, lower the temperature to 65-75℃, add 15-18wt% glycidol dropwise, and react at 65-75℃ for 2-3 hours. S3, Surface isocyanate treatment: The mixture obtained in S1 is placed in a fluidized bed and sprayed with an atomized acetone solution containing 5-6 wt% epoxy-modified polyurethane prepolymer. The temperature is controlled at 60-70℃ and the reaction is carried out for 45-60 minutes. S4, Expanded Microsphere Linkage: The S3 mixture with a mass ratio of 6-7:1 and the expanded microspheres are placed in a vacuum drum reactor and reacted at 40-50℃ for 1.5-2 hours. After the reaction is completed, the mixture is vacuum dried at 40-50℃ for 6-7 hours to obtain the whisker-fiber composite.

9. The non-shrink, single-component polyurethane grouting material according to claim 8, characterized in that: The method for preparing the expanded microspheres includes the following steps: S1, Kernel Synthesis: S11. Dissolve acrylic acid and acrylamide in water at a molar ratio of 7-8:3, add 0.4-0.5wt% methylenebisacrylamide, and heat to 65-75℃ under nitrogen protection; S12. Add 0.2-0.3wt% potassium persulfate solution dropwise, react for 3-4 hours, then centrifuge and wash. After centrifugation, vacuum dry at 40-50℃ for 3-4 hours. After drying, pulverize and sieve. S2, Microsphere Packaging: S21. Disperse the powder obtained in S1 in acetone, add 4-5wt% KH-550 and sonicate for 30min. S22. After ultrasonication, simultaneously add 8-10wt% acetone solution containing HDI type prepolymer and 0.1-0.2wt% dibutyltin dilaurate catalyst, react at 40-50℃ for 2h, centrifuge after reaction, and vacuum dry at 50-60℃ for 4h after centrifugation. S3, Surface epoxy functionalization: The solid obtained in S2 is dispersed in an acetone solution containing 3-5 wt% epichlorohydrin, refluxed at 60-70℃ for 3-4 hours, centrifuged and washed after reflux, and vacuum dried at 50℃ for 4 hours to obtain expanded microspheres.

10. A method for preparing a non-shrink, single-component polyurethane grout according to any one of claims 8-9, characterized in that, Includes the following steps: S1. Add the polyether polyol to the reactor and stir and dehydrate for 2-3 hours under vacuum at 90-130℃. S2. Reduce the temperature of the reactor from S1 to 65-75℃, add isocyanate under nitrogen protection, and react at 65-75℃ for 1.5h. S3. Reduce the temperature of the S2 reactor to 50-60℃, add plasticizer, catalyst, surfactant, flame retardant, hydrophilic agent, foam stabilizer, and whisker-fiber composite, and stir under nitrogen protection for 0.5-1h to obtain a non-shrinkage single-component waterborne polyurethane grouting material.

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