Coal-friendly pumpable anchoring agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of engineering reinforcement materials, in particular to a coal-friendly pumpable anchoring agent as well as a preparation method and application thereof. The anchoring agent is composed of a component A and a component B, wherein the component A comprises a first sodium silicate solution, a second sodium silicate solution, a catalyst, a chain extender, a thixotropic agent and a hydrophobic modified nano material; and the component B comprises isocyanate substances, a plasticizer, polyether polyol and super-hydrophobic small molecules. The preparation method comprises the following steps: respectively mixing and stirring the raw materials of the component A and the component B, and defoaming. According to the anchoring agent disclosed by the invention, the wettability and the interface bonding strength of the anchoring agent and the hydrophobic coal rock surface are remarkably improved by introducing the hydrophobic modified nano material and / or the super-hydrophobic small molecules and utilizing the dual effects of chemical bonds and hydrogen bonds. Meanwhile, the anchoring agent has the advantages of being low in viscosity, good in pumpability, adjustable in setting time, high in compressive strength, low in reaction temperature, environmentally friendly and the like, and is particularly suitable for anchor rod support of coal mine tunnels under complex geological conditions.

Description

Technical Field

[0001] This invention relates to the field of engineering reinforcement materials technology, and in particular to a coal-loving pumpable anchoring agent, its preparation method and application. Background Technology

[0002] As coal mining extends into deeper and more complex geological conditions, the stability of the surrounding rock in mine roadways is becoming increasingly prominent. Rock bolt support is the mainstream support method for coal mine roadways, but its effectiveness highly depends on the synergistic effect between the anchoring agent and the surrounding rock. Traditional cement mortar anchoring agents have weak adhesion to the coal seam interface, resulting in low anchoring strength. While widely used resin anchoring agents cure quickly and have high strength, they have weak affinity to the coal surface, easily forming a weak layer at the interface; furthermore, their high viscosity, poor fluidity, and poor pumpability make them difficult to effectively penetrate and anchor into developed coal seam fractures. Conventional anchoring agents are insufficient to meet the long-term support requirements of soft coal seams.

[0003] Therefore, developing a new type of anchoring agent that can effectively bond with the surface of coal and rock, and has both good pumpability and high anchoring strength is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a coal-affinity pumpable anchoring agent, its preparation method, and its application. The anchoring agent prepared by this invention, through specific component design, optimizes the affinity between the anchoring agent and the coal seam interface, enhances the compressive strength of the anchoring agent and its bonding strength with the coal seam, and can effectively prevent roof deformation and collapse. The modified anchoring agent has the characteristics of low viscosity and good fluidity, enabling long-distance pumping and deep penetration into coal seam fractures, thereby promoting the development of intelligent tunneling.

[0005] The technical solution adopted by this invention to solve its technical problem is: A coal-friendly pumpable anchoring agent, characterized in that it is composed of component A and component B, and is mixed in a volume ratio of 1:1 when used; The A component, by mass, comprises: 60-80 parts of a first sodium silicate solution, 20-40 parts of a second sodium silicate solution, 2-8 parts of a catalyst, 5-20 parts of a chain extender, 1-5 parts of a thixotropic agent, and 0.01-5 parts of hydrophobic modified nanomaterials. Component B, by mass, comprises: 90-110 parts isocyanate, 10-30 parts plasticizer, 2-6 parts polyether polyol, and 0.1-3 parts superhydrophobic small molecules.

[0006] Figure 1This is a schematic diagram illustrating the interaction between the anchoring agent of this invention and the coal-rock interface. Addressing the core pain points of existing anchoring agents—poor wettability and low bonding strength at the coal-rock interface, relying solely on weak physical interactions—this invention enhances affinity at the molecular level through a dual interaction of "chemical bonds + hydrogen bonds." The coal-rock surface is a complex heterogeneous surface where polar functional groups (hydrophilic) and non-polar hydrocarbon structures (hydrophobic) coexist. However, the large aromatic hydrocarbon structure makes the coal surface hydrophobic. To increase the wettability and chemical affinity between the anchoring agent and the coal seam surface, this invention introduces hydrophobically modified nanomaterials and superhydrophobic small molecules to achieve "molecular-level" bonding between the anchoring agent and the coal seam, rather than simple physical-mechanical anchoring.

[0007] This invention is based on existing water glass modified polyurethane anchoring agents. By specifically designing hydrophobic modifications for components A and B, and optimizing the component ratio and preparation process parameters, the anchoring agent system is hydrophobically modified. By utilizing the principle of similar polarity, the interfacial interaction force between the anchoring agent and the coal seam is enhanced.

[0008] Furthermore, the first sodium silicate solution is a sodium silicate solution with a modulus of 2.1 to 2.8 and a Baume degree of 45 to 51°Bé; The second sodium silicate solution is a sodium silicate solution with a modulus of 2.8 to 3.5 and a Baume degree of 40 to 45°Bé.

[0009] The selected sodium silicate solution is a mixture of solutions with different Baume degrees and moduli. Baume degree and modulus are important properties of sodium silicate solutions. The higher the modulus, the higher the silicon content and the stronger the adhesive force, but it will also be more difficult to dissolve in water. Therefore, it is important to select an appropriate modulus range. Baume degree indicates the concentration of the solution; the higher the concentration, the more sodium silicate and silicate it contains. By mixing sodium silicate solutions with different Baume degrees and moduli, the viscosity of component A can be controlled, resulting in a final anchoring agent with good flowability and adhesive force.

[0010] Furthermore, in component A, the hydrophobically modified nanomaterial is obtained by grafting and modifying the original nanomaterial with a hydrophobic modifier; the original nanomaterial is selected from one or more of nano-silica, carbon nanotubes, nano-calcium carbonate, nano-titanium dioxide, and nano-magnesium oxide. The hydrophobic modifier is selected from one or more of γ-methacryloxypropyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, 3-aminopropyltriethoxysilane, and octadecylamine.

[0011] After grafting with a specific hydrophobic modifier, the original nanomaterials can be effectively anchored in component A, enriching its surface with hydrophobic groups. When the anchoring agent comes into contact with the coal body, these hydrophobic groups can generate strong hydrophobic interactions and van der Waals forces with the non-polar structure on the coal body surface, significantly improving interfacial wettability and adhesion at the molecular level, thus solving the problem of poor affinity between traditional anchoring agents and coal body.

[0012] Further, in component A, the catalyst is selected from a complex system of tertiary amine catalysts and carboxylates, wherein the tertiary amine catalyst is selected from one or more of N,N-dimethylbenzylamine, N,N-dimethylcyclohexylamine, tetramethyl-1,6-hexanediamine, triethylenediamine, dimethylaminoethoxyethanol, and tetramethyldisyltriamine; and the carboxylate is selected from one or more of potassium acetate, potassium oleate, and potassium octanoate. The chain extender is selected from one or more of glycerol, isophorone diamine, and allyl propylene diamine; The thixotropic agent is selected from one or more of fumed silica, precipitated silica, silane-modified silica, organobentonite, and hydrogenated castor oil.

[0013] The catalyst (a complex system of tertiary amine catalysts and carboxylates) has high catalytic efficiency and is environmentally friendly and non-toxic, avoiding the environmental pollution problems of traditional organotin catalysts and improving the safety and environmental friendliness of the product. Chain extenders (such as glycerol) can effectively participate in and regulate the polymerization reaction network, enhance crosslinking density, and improve the strength and toughness of the cured body.

[0014] Thixotropic agents impart excellent thixotropic properties to the slurry, meaning it is thick at rest and thin under shear. This allows the anchoring agent to have good fluidity during pumping, and it can quickly recover its viscosity after being injected into rock fissures, preventing flow and ensuring the anchoring effect. This is the key to achieving "pumpability".

[0015] Furthermore, in component B, the isocyanate is selected from one or more of diphenylmethane diisocyanate (MDI), isophorone diisocyanate, triphenylmethane triisocyanate, trimer isocyanate, and polymethyl polyphenyl polyisocyanate. The plasticizer is selected from one or more of diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, dioctyl phthalate, and tributyl citrate; The superhydrophobic small molecule is one or more of trimethoxy(3,3,3-trifluoropropyl)silane, octadecyl isocyanate, n-octyltriethoxysilane, hexadecyltrimethoxysilane, etc.

[0016] Here, superhydrophobic small molecules are added to component B in a certain proportion to increase the hydrophobic properties of component B or to participate in the cross-linking reaction of component A, thereby increasing the hydrophobic properties of the anchoring system.

[0017] A method for preparing a coal-loving, pumpable anchoring agent as described above specifically includes the following steps: Step S1: Prepare sodium silicate solution: Weigh the first sodium silicate solution and the second sodium silicate solution according to the ratio, and mix them evenly to obtain a sodium silicate solution; Step S2: Preparation of component A: Weigh out the chain extender, catalyst, thixotropic agent and hydrophobic modified nanomaterials according to the ratio, mix them evenly to obtain a mixture, add the sodium silicate solution prepared in step S1 to the mixture, stir evenly and then degas to obtain component A. Step S3: Preparation of Component B: Weigh isocyanate, plasticizer, polyether polyol and superhydrophobic small molecule according to the ratio, stir evenly and then degas to obtain Component B.

[0018] The preparation method of this invention abandons the complex multi-step prepolymerization process of traditional polyurethane anchoring agents and adopts a "one-step" mechanical blending process, which is simple, stable and easy to industrialize.

[0019] Anchoring agent application: After mixing components A and B evenly in the specified proportions, use a pumping device to deliver the mixture to the required anchoring location.

[0020] Furthermore, in step S2, the mixing conditions for the chain extender, catalyst, thixotropic agent and hydrophobic modified nanomaterial are: stirring speed of 100-1000 rpm / min and stirring time of 10-60 min. The mixing conditions for the mixture and the sodium silicate solution are: a stirring speed of 100-1000 rpm / min and a stirring time of 30-60 min.

[0021] Furthermore, in step S3, the mixing conditions for isocyanate substances, plasticizers, polyether polyols and superhydrophobic small molecules are: stirring speed of 300 rpm / min and stirring time of 30 to 60 min.

[0022] The above process parameters ensure that the components are fully and evenly mixed, while avoiding the introduction of too many air bubbles or localized gelation due to excessively fast or slow shearing, thus guaranteeing the consistency and stability of the final product's performance.

[0023] Furthermore, in steps S2 and S3, the degassing process is one of vacuum centrifugal degassing, ultrasonic degassing, or static degassing. The specific operation of vacuum centrifugation degassing is as follows: the vacuum centrifugation degassing time is 1 to 5 minutes, and the vacuum degree is -0.1 MPa; The ultrasonic degassing time is 30–60 min; the static degassing time is 12–24 h.

[0024] Degassing treatment significantly reduces the air bubble content in the anchoring agent, resulting in a denser, less defective cured anchor structure, directly improving its compressive strength and durability. The availability of multiple degassing options also increases the flexibility and adaptability of the process.

[0025] An application of the above-mentioned coal-friendly pumpable anchoring agent, wherein the anchoring agent is used in rock and soil anchoring in coal mine roadways, water conservancy and hydropower projects, underground engineering or subway tunnels.

[0026] The beneficial effects of this invention are as follows: This invention has a reasonable design and a simple preparation method, and has the following advantages: (1) The coal-friendly pumpable anchoring agent prepared by the present invention has good fluidity and bonding strength, which can effectively enhance the connection between the anchor and the coal and rock strata; the bonding strength with the coal strata is above 5MPa, and the compressive strength of the anchor body can reach above 55MPa. The anchor body has high compressive strength and good toughness, which can meet most engineering requirements and is very suitable for coal and rock strata geological anchoring with high requirements. (2) The coal-friendly pumpable anchoring agent prepared by the present invention has a low reaction temperature and no high temperature safety hazard; at the same time, it does not contain organic flame retardant components, does not contain metal catalysts, has low VOCs, is a green and environmentally friendly material, and has no impact on the environment after being injected into the formation, which meets the requirements of green and environmental protection. (3) The preparation method of the coal-loving pumpable anchoring agent obtained by the present invention is simple and easy to operate. The raw materials used are simple and do not require prepolymerization treatment, thereby reducing costs and energy consumption. In addition, small molecule TDI (toluene diisocyanate) is not used in the raw materials of the formula, which avoids the instability risk caused by its volatility, high reactivity and potential toxicity, and the performance is more stable during storage and use. (4) The cohesive pumpable anchoring agent prepared by the present invention has an adjustable setting time. The reaction rate can be easily adjusted by controlling the amount of catalyst, and fast, medium and slow thixotropic anchoring agents with different setting times can be obtained. The fastest can reach initial setting in about 20 seconds. According to the operation requirements of the pumpable anchoring agent, the material curing time can be controlled in 2 to 3 minutes. (5) The coal-friendly pumpable anchoring agent A and B obtained by the present invention does not react with water during the mixing reaction process, and can quickly solidify and form underwater, with little impact on strength, and can strengthen coal and rock mass in a water environment. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Figure 1 This is a schematic diagram illustrating the interaction between the anchoring agent and the coal-rock interface of the present invention; Figure 2 This is a comparison diagram of the contact angles of the anchoring agent prepared in Example 1 and the unmodified anchoring agent in Comparative Example 3. Figure 3 These are microscopic morphology images of the anchoring agent prepared in Example 1 and the unmodified anchoring agent in Comparative Example 3. Figure 4 This is a graph showing the compressive strength of the anchoring agent prepared in Example 1 and the unmodified anchoring agent in Comparative Example 3. Figure 5 This is a test diagram of the bonding strength between the anchoring agent prepared in Example 1 and the coal seam; Figure 6 These are microscopic morphology images of the bonding cross sections between the anchoring agent and the coal seam obtained in Example 1 and Comparative Example 3. Detailed Implementation

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In a first aspect, the present invention provides a coal-loving pumpable anchoring agent, which is composed of component A and component B, and is mixed in a volume ratio of 1:1 when used. Component A, by mass, includes: 60-80 parts of first sodium silicate solution, 20-40 parts of second sodium silicate solution, 2-8 parts of catalyst, 5-20 parts of chain extender, 1-5 parts of thixotropic agent, and 0.01-5 parts of hydrophobic modified nanomaterials. Component B, by mass, includes: 90-110 parts isocyanate, 10-30 parts plasticizer, 2-6 parts polyether polyol, and 0.1-3 parts superhydrophobic small molecules.

[0034] The first sodium silicate solution is a sodium silicate solution with a modulus of 2.1 to 2.8 and a Baume degree of 45 to 51°Bé; the second sodium silicate solution is a sodium silicate solution with a modulus of 2.8 to 3.5 and a Baume degree of 40 to 45°Bé.

[0035] The mass ratio of the first sodium silicate solution to the second sodium silicate solution is 7:3. This specific mass ratio was determined based on extensive experiments, enabling the two sodium silicate solutions to work synergistically in the anchoring agent, balancing the early and later strength development of the anchoring agent, while ensuring good fluidity and pumpability, thus improving the overall performance of the anchoring agent.

[0036] In component A, the hydrophobically modified nanomaterial is obtained by grafting and modifying the original nanomaterial with a hydrophobic modifier; the original nanomaterial is selected from one or more of nano-silica (particle size of 30-500nm), carbon nanotubes (length of 1-30μm), nano-calcium carbonate, nano-titanium dioxide, and nano-magnesium oxide; the hydrophobic modifier is selected from one or more of γ-methacryloyloxypropyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, 3-aminopropyltriethoxysilane, and octadecylamine.

[0037] In component A, the catalyst is selected from a complex system of tertiary amine catalysts and carboxylates. The tertiary amine catalyst is selected from one or more of N,N-dimethylbenzylamine, N,N-dimethylcyclohexylamine, tetramethyl-1,6-hexanediamine, triethylenediamine, dimethylaminoethoxyethanol, and tetramethyldipropylenetriamine. The carboxylate is selected from one or more of potassium acetate, potassium oleate, and potassium octanoate. The chain extender is selected from one or more of glycerol, isophorone diamine, and methylallylpropylene diamine. The thixotropic agent is selected from one or more of fumed silica, precipitated silica, silane-modified silica, organobentonite, and hydrogenated castor oil.

[0038] In component B, the isocyanate is selected from one or more of diphenylmethane diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, trimer isocyanate, and polymethyl polyphenyl polyisocyanate. The plasticizer is selected from one or more of diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, dioctyl phthalate, and tributyl citrate. The superhydrophobic small molecule is one or more of trimethoxy(3,3,3-trifluoropropyl)silane, octadecyl isocyanate, n-octyltriethoxysilane, and hexadecyltrimethoxysilane. The polyether polyol is selected from one or more of DL1000D, DL2000D, and silane-modified polyether polyols.

[0039] Secondly, the present invention provides a method for preparing the above-mentioned coal-loving pumpable anchoring agent, specifically including the following steps: Step S1: Prepare sodium silicate solution: Weigh the first sodium silicate solution and the second sodium silicate solution according to the ratio, and mix them evenly to obtain a sodium silicate solution; Step S2: Preparation of component A: Weigh out the chain extender, catalyst, thixotropic agent and hydrophobic modified nanomaterials according to the ratio, mix them evenly to obtain a mixture, add the sodium silicate solution prepared in step S1 to the mixture, stir evenly and then degas to obtain component A. Step S3: Preparation of Component B: Weigh isocyanate, plasticizer, polyether polyol and superhydrophobic small molecule according to the ratio, stir evenly and then degas to obtain Component B.

[0040] In step S2, the mixing conditions for the chain extender, catalyst, thixotropic agent and hydrophobically modified nanomaterial are: stirring speed of 100-1000 rpm / min and stirring time of 10-60 min; the mixing conditions for the mixture and sodium silicate solution are: stirring speed of 100-1000 rpm / min and stirring time of 30-60 min.

[0041] In step S3, the mixing conditions for isocyanate substances, plasticizers, polyether polyols and superhydrophobic small molecules are: stirring speed of 300 rpm / min and stirring time of 30 to 60 min.

[0042] In steps S2 and S3, the degassing process is one of vacuum centrifugation degassing, ultrasonic degassing, or static degassing. The specific operation of vacuum centrifugation degassing is as follows: the vacuum centrifugation degassing time is 1 to 5 minutes and the vacuum degree is -0.1 MPa; the ultrasonic degassing time is 30 to 60 minutes; and the static degassing time is 12 to 24 hours.

[0043] Degassing treatment can effectively remove air bubbles generated during the preparation of anchoring agents, avoiding the adverse effects of air bubbles on the strength and durability of anchoring agents, and improving the quality and performance of anchoring agents.

[0044] Thirdly, the present invention also provides the application of the above-mentioned coal-friendly pumpable anchoring agent, which is used in rock and soil anchoring in coal mine roadways, water conservancy and hydropower projects, underground engineering or subway tunnels.

[0045] The catalysts used in the following examples are all N,N-dimethylbenzylamine and potassium oleate in a mass ratio of 1:5.

[0046] Example 1 The coal-loving pumpable anchoring agent of this embodiment is composed of component A and component B, which are mixed at a volume ratio of 1:1 when used. Component A: 100 parts sodium silicate solution, 12 parts glycerol, 1 part hydrogenated castor oil, 4 parts catalyst, and 2 parts octadecyltrimethoxysilane-modified nano-silica; Component B: 100 parts polymethyl polyphenyl polyisocyanate, 10 parts diethylene glycol butyl ether acetate, 5 parts polyether polyol DL2000D, and 0.5 parts hexadecyltrimethoxysilane.

[0047] The preparation method of the above-mentioned coal-loving pumpable anchoring agent specifically includes the following steps: Step S1: Prepare sodium silicate solution: Weigh the first sodium silicate solution and the second sodium silicate solution at a mass ratio of 7:3, and mix them evenly to obtain the sodium silicate solution. Step S2: Preparation of component A: Take 12 parts of glycerol, 4 parts of catalyst, 1 part of hydrogenated castor oil, and 2 parts of modified nano-silica and add them to a mixer in sequence. Stir at 300 rpm / min for 15 min. Then add 100 parts of pre-mixed sodium silicate solution and stir at 600 rpm / min for 30 min. Degas under vacuum for 3 min to obtain component A. Step S3: Preparation of Component B: Take 100 parts of polymethyl polyphenyl polyisocyanate, 10 parts of diethylene glycol butyl ether acetate, 5 parts of polyether polyol DL2000D and 0.5 parts of hexadecyltrimethoxysilane and add them to a mixer in sequence. Stir at 300 rpm / min for 30 min and then degas under vacuum for 3 min to obtain Component B.

[0048] Example 2 The coal-loving pumpable anchoring agent of this embodiment is composed of component A and component B, which are mixed at a volume ratio of 1:1 when used. Component A: 100 parts sodium silicate solution, 12 parts glycerol, 1 part hydrogenated castor oil, 4 parts catalyst, 0.05 parts octadecylamine-modified carbon nanotubes; Component B: 100 parts polymethyl polyphenyl polyisocyanate, 10 parts diethylene glycol butyl ether acetate, 5 parts polyether polyol DL2000D, and 1.5 parts hexadecyltrimethoxysilane.

[0049] The preparation method of the above-mentioned coal-loving pumpable anchoring agent specifically includes the following steps: Step S1: Prepare sodium silicate solution: Weigh the first sodium silicate solution and the second sodium silicate solution at a mass ratio of 7:3, and mix them evenly to obtain the sodium silicate solution. Step S2: Preparation of component A: Take 12 parts of glycerol, 4 parts of catalyst, 1 part of hydrogenated castor oil, and 0.05 parts of modified carbon nanotubes and add them to a mixer in sequence. Stir at 200 rpm / min for 20 min. Then add 100 parts of pre-mixed sodium silicate solution and stir at 1000 rpm / min for 15 min. Degas under vacuum for 3 min to obtain component A. Step S3: Preparation of Component B: Take 100 parts of polymethyl polyphenyl polyisocyanate, 10 parts of diethylene glycol butyl ether acetate, 5 parts of polyether polyol DL2000D and 1.5 parts of hexadecyltrimethoxysilane and add them to a mixer in sequence. Stir at 500 rpm / min for 10 min and then degas under vacuum for 3 min to obtain Component B.

[0050] Example 3 The coal-loving pumpable anchoring agent of this embodiment is composed of component A and component B, which are mixed at a volume ratio of 1:1 when used. Component A: 100 parts sodium silicate solution, 12 parts glycerol, 1 part hydrogenated castor oil, 4 parts catalyst, 0.1 parts octadecylamine-modified carbon nanotubes; Component B: 100 parts polymethyl polyphenyl polyisocyanate, 10 parts diethylene glycol butyl ether acetate, 5 parts polyether polyol DL2000D, and 1 part octadecyl isocyanate.

[0051] The preparation method of the above-mentioned coal-loving pumpable anchoring agent specifically includes the following steps: Step S1: Prepare sodium silicate solution: Weigh the first sodium silicate solution and the second sodium silicate solution at a mass ratio of 7:3, and mix them evenly to obtain the sodium silicate solution. Step S2: Preparation of component A: Take 12 parts of glycerol, 4 parts of catalyst, 1 part of hydrogenated castor oil, and 0.1 parts of octadecylamine-modified carbon nanotubes and add them to a mixer in sequence. Stir at 300 rpm / min for 15 min. Then add 100 parts of pre-mixed sodium silicate solution and stir at 600 rpm / min for 30 min. Degas under vacuum for 3 min to obtain component A. Step S3: Preparation of Component B: Take 100 parts of polymethyl polyphenyl polyisocyanate, 10 parts of diethylene glycol butyl ether acetate, 5 parts of polyether polyol DL2000D and 1 part of octadecyl isocyanate and add them to a mixer in sequence. Stir at 300 rpm / min for 30 min and then degas under vacuum for 3 min to obtain Component B.

[0052] Comparative Example 1 The only difference from Example 1 is that no superhydrophobic small molecules are added to component B; otherwise, they are the same as in Example 1.

[0053] Comparative Example 2 The only difference from Example 1 is that hydrophobic modified nanomaterials are not added to component A; otherwise, they are the same as in Example 1.

[0054] Comparative Example 3 Compared with Example 1, the only difference is that hydrophobic modified nanomaterials are not added to component A, and superhydrophobic small molecules are not added to component B. Everything else is the same as Example 1.

[0055] Application Example 1 In Example 1, after components A and B are thoroughly mixed at a volume ratio of 1:1, they are molded underwater and the metal ingot is bonded to the water-bearing coal and rock.

[0056] Application Example 2 In Example 1, components A and B were thoroughly mixed at a volume ratio of 1:1 and then solidified at 10°C.

[0057] Anchoring tests were conducted on the anchoring agents prepared in Examples 1 to 3, Comparative Examples 1 to 3, and Application Examples 1 to 2, respectively. The test methods and standards were in accordance with "Polymer Materials for Reinforcing Coal and Rock Masses in Coal Mines".

[0058] The performance data of Examples 1 to 3, Comparative Examples 1 to 3, and Application Examples 1 to 2 at room temperature are shown in Table 1.

[0059] Table 1 Test Results

[0060] As can be seen from the data in Table 1: (1) The introduction of hydrophobic modified materials did not significantly affect the initial viscosity of the anchoring agent, effectively ensuring the fluidity and pumpability of the slurry after mixing. (2) Compared with Comparative Example 3, the hydrophobic modified anchoring agent of Experimental Example 1 showed an increase of about 100% in bonding strength with coal and rock, and an increase of 18% in compressive strength of the anchor body, which significantly improved mechanical properties. (3) Comparison of Comparative Example 1 and Comparative Example 2 confirms that the hydrophobic modification effect of component A is better than that of component B; while the simultaneous modification of components A and B shows a synergistic enhancement effect. (4) The results of Application Examples 1 and 2 show that the anchoring agent prepared in Example 1 is suitable for harsh environments: it can be quickly cured underwater and the bonding strength with water-bearing coal and rock reaches 4.6 MPa, making it suitable for water-bearing environments; in low-temperature environments, it only prolongs the curing time without damaging the final performance, and this problem can be improved by formula optimization.

[0061] Figure 2This is a comparison of the contact angles of the anchoring agent prepared in Example 1 and the unmodified anchoring agent in Comparative Example 3. The figure shows that when components A and B are mechanically blended at a volume ratio of 1:1 for 30 seconds, the contact angle of the solidified anchoring agent increases from 70–80° before modification to 130–140°, significantly improving its wettability with the coal seam. The mechanism of this contact angle comparison is as follows: In the anchoring agent system, the ether bonds, urethane bonds, and urea bonds of the polyether segments can form hydrogen bonds with the hydroxyl groups on the coal surface, exhibiting strong adsorption. Furthermore, the long carbon chains of the polyether polyol, the carbon chain structure of the polymethyl polyphenyl polyisocyanate, and the introduction of hydrophobic segments such as octadecyl groups can form hydrophobic interactions with the non-polar groups on the coal surface, enhancing the wettability of the anchoring agent with the coal. Meanwhile, the isocyanate groups can chemically react with the hydroxyl or carboxyl groups on the surface of the coal seam to form a chemical bridge between the polyurethane and the coupling agent and the coal and rock, thereby further improving the interfacial bonding strength between the anchoring agent and the coal and rock.

[0062] Figure 3 The figures show the microstructure of the anchoring agent prepared in Example 1 and the unmodified anchoring agent in Comparative Example 3. As can be seen from the figures, the modified anchoring agent has a denser internal structure and a significantly reduced pore size, which can significantly improve the compressive strength and bond strength of the anchoring agent.

[0063] Figure 4 This is a graph showing the compressive strength of the anchoring agent prepared in Example 1 and the unmodified anchoring agent in Comparative Example 3. The graph shows that the modified anchoring agent exhibits significant improvements in both compressive strength and toughness.

[0064] Figure 5 This is a test diagram of the bonding strength between the anchoring agent prepared in Example 1 and the coal seam; Figure 6 These are microscopic morphology images of the bonding cross-sections between the anchoring agents prepared in Example 1 and Comparative Example 3 and the coal seam. Microscopic morphology analysis shows that the hydrophobically modified anchoring agent has a denser bond with the coal and rock interface, with a blurred interface between the two. In contrast, the unmodified anchoring agent has a clear interface with the coal and rock, exhibiting obvious pores and gaps, and a poorer bonding degree.

[0065] The anchoring agent prepared in Example 1 was applied to a roadway support site at a depth of 600 meters in a coal mine. The roof of this area consisted of a low-strength, coal-rich stratum. High-strength hollow grouting anchor cables with diameters of 21.8 × 4000 mm were used. Components A and B of the anchoring agent were separately connected to a two-component pumping system and mixed and pumped at a volume ratio of 1:1. The pumping pressure was stabilized at 5–10 MPa.

[0066] The construction process showed that the entire pumping and grouting process was continuous and stable, without any blockages or leakage. The grouting time for a single hole was approximately 2 minutes, demonstrating the material's excellent adaptability to construction. The anchoring agent reached the required early strength to support the material one hour after grouting. After 24 hours, three anchor cables were randomly selected for destructive tension tests. The results showed that their breaking loads all exceeded 230 kN, meeting the design requirement of 200 kN, proving that it achieved reliable anchoring for fractured coal and rock masses.

[0067] In summary, the anchoring agent of this invention, by introducing hydrophobically modified nanomaterials and / or superhydrophobic small molecules, significantly improves the wettability and interfacial bonding strength between the anchoring agent and the hydrophobic coal and rock surface through the dual effects of "chemical bonds + hydrogen bonds". Simultaneously, this anchoring agent possesses advantages such as low viscosity, good pumpability, adjustable setting time, high compressive strength, low reaction temperature, and environmental friendliness, making it particularly suitable for anchor bolt support in coal mine roadways under complex geological conditions.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coal-loving, pumpable anchoring agent, characterized in that: It consists of component A and component B, which should be mixed in a 1:1 volume ratio before use. The A component, by mass, comprises: 60-80 parts of a first sodium silicate solution, 20-40 parts of a second sodium silicate solution, 2-8 parts of a catalyst, 5-20 parts of a chain extender, 1-5 parts of a thixotropic agent, and 0.01-5 parts of hydrophobically modified nanomaterials. Component B, by mass, comprises: 90-110 parts isocyanate, 10-30 parts plasticizer, 2-6 parts polyether polyol, and 0.1-3 parts superhydrophobic small molecules.

2. The coal-loving pumpable anchoring agent according to claim 1, characterized in that: The first sodium silicate solution is a sodium silicate solution with a modulus of 2.1 to 2.8 and a Baume degree of 45 to 51°Bé. The second sodium silicate solution is a sodium silicate solution with a modulus of 2.8 to 3.5 and a Baume degree of 40 to 45°Bé.

3. The coal-loving pumpable anchoring agent according to claim 1, characterized in that: In component A, the hydrophobically modified nanomaterial is obtained by grafting and modifying the original nanomaterial with a hydrophobic modifier; the original nanomaterial is selected from one or more of nano-silica, carbon nanotubes, nano-calcium carbonate, nano-titanium dioxide, and nano-magnesium oxide. The hydrophobic modifier is selected from one or more of γ-methacryloxypropyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, 3-aminopropyltriethoxysilane, and octadecylamine.

4. The coal-loving pumpable anchoring agent according to claim 1, characterized in that: In component A, the catalyst is selected from a complex system of tertiary amine catalysts and carboxylates, wherein the tertiary amine catalyst is selected from one or more of N,N-dimethylbenzylamine, N,N-dimethylcyclohexylamine, tetramethyl-1,6-hexanediamine, triethylenediamine, dimethylaminoethoxyethanol, and tetramethyldisyltriamine; and the carboxylate is selected from one or more of potassium acetate, potassium oleate, and potassium octanoate. The chain extender is selected from one or more of glycerol, isophorone diamine, and allyl propylene diamine; The thixotropic agent is selected from one or more of fumed silica, precipitated silica, silane-modified silica, organobentonite, and hydrogenated castor oil.

5. The coal-loving pumpable anchoring agent according to claim 1, characterized in that: In component B, the isocyanate is selected from one or more of diphenylmethane diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, trimer isocyanate, and polymethyl polyphenyl polyisocyanate. The plasticizer is selected from one or more of diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, dioctyl phthalate, and tributyl citrate; The superhydrophobic small molecule is one or more of perfluorooctyltriethoxysilane, trimethoxy(3,3,3-trifluoropropyl)silane, heptadecafluorodecyltrimethoxysilane, octadecyl isocyanate, etc.

6. A method for preparing a coal-loving, pumpable anchoring agent as described in any one of claims 1 to 5, characterized in that: Specifically, the steps include the following: Step S1: Prepare sodium silicate solution: Weigh the first sodium silicate solution and the second sodium silicate solution according to the ratio, and mix them evenly to obtain a sodium silicate solution; Step S2: Preparation of component A: Weigh out the chain extender, catalyst, thixotropic agent and hydrophobic modified nanomaterials according to the ratio, mix them evenly to obtain a mixture, add the sodium silicate solution prepared in step S1 to the mixture, stir evenly and then degas to obtain component A. Step S3: Preparation of Component B: Weigh isocyanate, plasticizer, polyether polyol and superhydrophobic small molecule according to the ratio, stir evenly and then degas to obtain Component B.

7. The method for preparing the coal-loving pumpable anchoring agent according to claim 6, characterized in that: In step S2, the mixing conditions for the chain extender, catalyst, thixotropic agent and hydrophobically modified nanomaterial are: stirring speed of 100-1000 rpm / min and stirring time of 10-60 min. The mixing conditions for the mixture and the sodium silicate solution are: a stirring speed of 100-1000 rpm / min and a stirring time of 30-60 min.

8. The method for preparing the coal-loving pumpable anchoring agent according to claim 6, characterized in that: In step S3, the mixing conditions for isocyanate substances, plasticizers, polyether polyols and superhydrophobic small molecules are: stirring speed of 300 rpm / min and stirring time of 30 to 60 min.

9. The method for preparing the coal-loving pumpable anchoring agent according to claim 6, characterized in that: In steps S2 and S3, the degassing process is one of vacuum centrifugal degassing, ultrasonic degassing, and static degassing. The specific operation of vacuum centrifugation degassing is as follows: the vacuum centrifugation degassing time is 1 to 5 minutes, and the vacuum degree is -0.1 MPa; The ultrasonic degassing time is 30–60 min; the static degassing time is 12–24 h.

10. The application of a coal-loving pumpable anchoring agent as described in any one of claims 1 to 5, characterized in that: The anchoring agent is used in rock and soil anchoring in coal mine roadways, water conservancy and hydropower projects, underground engineering, or subway tunnels.

Images