Kaimian reinforcing material at 37 degrees celsius and preparation method thereof

Abstract

This application relates to the technical field of mining reinforcement materials, specifically disclosing a 37℃ Keminan reinforcement material and its preparation method. The 37℃ Keminan reinforcement material comprises the following raw materials in parts by weight: 45-65 parts thermosetting phenolic resin, 3-8 parts epoxy diluent, 3-6 parts composite curing agent, 0.5-1.5 parts coupling agent, 15-30 parts ultrafine calcium carbonate, 1-3 parts nano-silica, 0.3-1 parts thixotropic agent, and 5-12 parts flame retardant. The composite curing agent is a microencapsulated curing agent combined with unencapsulated 2-ethyl-4-methylimidazole, exhibiting good latent stability at room temperature. At 37℃, the capsule wall ruptures, releasing the active component, which synergistically works with the unencapsulated imidazole to rapidly reduce the crosslinking activation energy of the phenolic resin, achieving full curing at low temperatures.

Description

Technical Field

[0001] This application relates to the field of mining reinforcement materials technology, and more specifically, it relates to a 37°C Kemin reinforcement material and its preparation method. Background Technology

[0002] As a crucial basic energy source in my country, the safe and efficient mining of coal has always been a core concern for the industry. Among the key aspects of coal mine safety, support operations such as underground reinforcement of fractured coal and rock masses, fissure plugging, roof maintenance, and goaf filling are crucial for ensuring safe production. The effectiveness of grouting reinforcement of underground fractured coal and rock masses directly determines the critical force transmission carrier between roadway support structures. The interface bonding state and penetration consolidation capacity between the grouting reinforcement and the coal and rock mass are essential for ensuring the overall load-bearing capacity of the support structure and preventing safety accidents such as spalling, roof collapse, and surrounding rock instability.

[0003] Patent application CN110818371A discloses an inorganic reinforcement material for high-speed mining (Kemian IV), comprising component A and component B, with the components mixed in the following mass fractions: component A includes 575-625 parts calcium sulfoaluminate, 70-90 parts gypsum powder, and 265-350 parts silicate cement; component B includes 690-720 parts slag silicate cement, 285-315 parts ultrafine cement, and 1-8 parts retarder. This application provides an inorganic cement-based reinforcement material that relies solely on the cementitious properties of cement hydration products to form a physical bond with the rock surface. It cannot penetrate into micro-cracks and lacks interfacial reinforcement components, resulting in low interfacial bonding strength with the coal and rock mass. Under surrounding rock stress, it is prone to interfacial debonding, cracking, and slippage, leading to the failure of the support system. Organic reinforcement materials rely on chemical penetration and molecular cross-linking for anchoring, which can penetrate deep into the micro-fractures of the rock mass to form an integral bond. The bonding strength is much higher than that of inorganic reinforcement materials that rely on physical bonding. The interface is not easy to debond, and the reinforcement is more reliable.

[0004] Phenolic resins possess excellent mechanical strength, water resistance, corrosion resistance, and flame retardant properties. They are also widely available and cost-effective, making them a core matrix material for organic reinforcement materials used in mining. They demonstrate promising application potential in underground engineering and mine support. However, traditional phenolic resin-based reinforcement materials generally have high curing temperatures, typically requiring 130-150℃. In environments with temperatures close to 37℃ (such as deep mines affected by geothermal activity or the surrounding working environment), effective curing is impossible due to high activation, or the curing time is excessively long, severely impacting construction efficiency. Furthermore, cured materials are prone to shrinkage cracking and insufficient toughness, making them unsuitable for adapting to the deformation requirements of fractured rock masses underground. Summary of the Invention

[0005] In order to reduce the curing temperature of phenolic resin-based reinforcement materials to adapt to construction scenarios without heating conditions in wells, this application provides a 37℃ Kemin reinforcement material and its preparation method.

[0006] Firstly, this application provides a 37℃ Keminian reinforcement material, employing the following technical solution: A 37℃ Kemin reinforcement material comprises the following raw materials in parts by weight: 45-65 parts thermosetting phenolic resin, 3-8 parts epoxy diluent, 3-6 parts composite curing agent, 0.5-1.5 parts coupling agent, 15-30 parts ultrafine calcium carbonate, 1-3 parts nano silica, 0.3-1 parts thixotropic agent, and 5-12 parts flame retardant; The preparation method of the composite curing agent includes the following steps: (1) Mix 2-ethyl-4-methylimidazolium and hydroxyethyl propylene glycol diglycidyl ether in a mass ratio of (4-6):(2-3) to obtain a core mixture; mix citric acid and polyurea-formaldehyde resin wall material in a mass ratio of 1:(2-3) to obtain a wall mixture; (2) Mix 65-75 parts by weight of the capsule core mixture, 25-35 parts by weight of the capsule wall mixture and 100-160 parts by weight of deionized water to form a suspension; spray dry the suspension under the conditions of inlet air temperature of 120-150℃, outlet air temperature of 60-80℃ and atomization pressure of 0.2-0.3MPa to form microcapsules; sieve and dry the microcapsules to obtain a microcapsule curing agent; (3) Mix 70-80 parts by weight of microcapsule curing agent with 20-30 parts by weight of 2-ethyl-4-methylimidazole to obtain a composite curing agent.

[0007] By adopting the above technical solution, this application uses a composite curing agent formed by combining a microcapsule curing agent with uncoated 2-ethyl-4-methylimidazole. The microcapsules have 2-ethyl-4-methylimidazole and hydroxyethyl propylene glycol diglycidyl ether as the core and citric acid and polyurea-formaldehyde resin as the shell. By reasonably controlling the ratio of the core to the shell and the spray drying process, the composite curing agent has good latent stability at room temperature. At 37°C, the shell ruptures and releases the active components, which work synergistically with the uncoated imidazole to rapidly reduce the crosslinking activation energy of the phenolic resin, thus achieving full curing at low temperature.

[0008] Through the synergistic effect of the composite curing agent and the overall formula, this application reduces the curing temperature of the reinforcement material to 37°C, which can be used directly in the mine without heating. The material's applicable period and curing speed match the on-site construction requirements. The material can penetrate the micro-fractures of the rock mass and form a molecular-level chemical bond with the coal and rock mass. The interface is firmly bonded, effectively solving the problems of weak physical bonding, easy debonding, and poor reinforcement reliability of traditional inorganic chemiluminescent materials.

[0009] Preferably, in step (1), 2-ethyl-4-methylimidazole and hydroxyethyl propylene glycol diglycidyl ether are mixed in a mass ratio of (4-6):(2-3), and then propylene oxide block polyether emulsifier is added. The mixture is stirred at 30-40°C for 10-20 minutes to obtain a core mixture. The amount of propylene oxide block polyether emulsifier added is 0.5%-1.5% of the total mass of 2-ethyl-4-methylimidazole and hydroxyethyl propylene glycol diglycidyl ether.

[0010] By adopting the above technical solution, the propylene oxide block polyether emulsifier can effectively reduce the interfacial tension between 2-ethyl-4-methylimidazole and hydroxyethyl propylene glycol diglycidyl ether, promote rapid and uniform mixing of the two, avoid local agglomeration, and improve the dispersion stability of the capsule core mixture, laying a good foundation for subsequent microcapsule encapsulation.

[0011] Preferably, in step (1), citric acid and polyurea-formaldehyde resin wall material are mixed in a mass ratio of 1:(2-3), and then polyvinyl alcohol is added to mix to obtain a capsule wall mixture; the amount of polyvinyl alcohol added is 1%-2% of the total mass of citric acid and polyurea-formaldehyde resin wall material.

[0012] By adopting the above technical solution, polyvinyl alcohol, as a dispersant and film-forming aid, can significantly improve the dispersion uniformity of citric acid in polyurea-formaldehyde resin wall materials, avoiding the formation of defects in the capsule wall due to local aggregation of organic acids; at the same time, polyvinyl alcohol can enhance the film-forming performance of polyurea-formaldehyde resin, enabling the capsule wall to form a denser and more uniform film structure during subsequent spray drying. This can effectively shield the active components inside the capsule core, ensuring stability during room temperature storage, and can also precisely match the temperature-sensitive response characteristics at 37°C, ensuring rapid softening and cracking at the target temperature, releasing the active components of the capsule core, and achieving low-temperature curing triggering.

[0013] Preferably, in step (2), 65-75 parts by weight of the capsule core mixture, 25-35 parts by weight of the capsule wall mixture, 100-160 parts by weight of deionized water and 0.3-0.8 parts by weight of fumed silica are mixed to form a suspension; the suspension is spray-dried under the conditions of inlet air temperature of 120-150℃, outlet air temperature of 60-80℃ and atomization pressure of 0.2-0.3MPa to form microcapsules; the microcapsules are sieved and dried to obtain a microcapsule curing agent.

[0014] By adopting the above technical solution, fumed silica has excellent dispersion and stabilization effects, which can effectively prevent the core mixture and the shell mixture from separating and settling in the suspension, ensuring the uniform bonding of the core and shell during spray drying and improving the encapsulation rate of microcapsules. At the same time, fumed silica can adjust the viscosity of the suspension to meet the process requirements of spray drying, avoiding problems such as uneven atomization and excessive microcapsule particle size deviation during spraying. Finally, a microcapsule curing agent with uniform particle size and complete shell is prepared, further ensuring the latency and low-temperature response consistency of the composite curing agent.

[0015] Preferably, in step (3), 40-60 parts by weight of microcapsule curing agent, 20-30 parts by weight of 2-ethyl-4-methylimidazole and 20-30 parts by weight of hydroxyethyl propylene glycol diglycidyl ether are mixed to obtain a composite curing agent.

[0016] By adopting the above technical solution, while retaining the room-temperature latency advantage of microcapsule curing agents, an appropriate amount of unencapsulated 2-ethyl-4-methylimidazole and hydroxyethyl propylene glycol diglycidyl ether are added. The synergistic effect of the two can further reduce the crosslinking activation energy of phenolic resin, accelerate the curing rate at 37°C, and ensure a more complete curing reaction, thus solving the problems of slow curing start-up and incomplete curing of microcapsule curing agents alone. At the same time, the unencapsulated hydroxyethyl propylene glycol diglycidyl ether can synergize with the activator released in the core, further increasing the crosslinking density of the curing system, enhancing the compatibility between the composite curing agent and the phenolic resin system, and ultimately improving the mechanical strength, bonding strength, and curing stability of the reinforced material, better meeting the needs of downhole 37°C unheated construction scenarios.

[0017] Preferably, the epoxy diluent is a mixture of butyl glycidyl ether and phenyl glycidyl ether in a mass ratio of (2-3):1.

[0018] By adopting the above technical solution, the specially formulated glycidyl ether epoxy diluent can not only effectively reduce the viscosity of the thermosetting phenolic resin system, improve the fluidity of the material and the penetration ability of downhole grouting, and facilitate penetration into the micro-fractures of coal and rock masses; at the same time, its epoxy groups can undergo synergistic cross-linking reaction with phenolic resin and curing agent components, avoiding the decrease in material mechanical properties caused by simple diluents, taking into account both the fluidity of the system and the mechanical strength after curing, adapting to complex downhole grouting conditions, and further improving the penetration and consolidation effect of the reinforcement material.

[0019] Preferably, the coupling agent is prepared by blending KH-550, KH-560 and an ethanol solution, wherein the mass ratio of KH-550 to KH-560 is 1:1.

[0020] By adopting the above technical solutions, KH-550 and KH-560 can be used in combination to achieve synergistic effects: KH-550 can enhance the interfacial bonding force between organic resin and inorganic filler (ultrafine calcium carbonate, nano silica), and KH-560 can undergo cross-linking reaction with the active groups of phenolic resin, further improving the compatibility of the organic-inorganic interface.

[0021] Preferably, the thixotropic agent is a mixture of hydrophobic fumed silica and modified organobentonite in a mass ratio of (1-2):1; the modified organobentonite is obtained by modifying sodium-based bentonite with an aqueous solution of hexadecyltrimethylammonium chloride.

[0022] By adopting the above technical solution, the combination of hydrophobic fumed silica and modified organic bentonite can significantly improve the thixotropic properties and suspension stability of the reinforcement material. The material is less prone to sedimentation and stratification during grouting, which facilitates construction operations. At the same time, the thixotropic agent can form a three-dimensional network structure after the material is cured, which enhances the toughness and crack resistance of the material, reduces shrinkage cracking defects during the curing process, adapts to the deformation requirements of underground fractured coal and rock masses, and further improves the integrity and reliability of the reinforcement system.

[0023] Preferably, the flame retardant is a mixture of aluminum hydroxide and melamine urate in a mass ratio of (3-4):1.

[0024] Secondly, this application provides a method for preparing a 37℃ Keminian reinforcement material, which adopts the following technical solution: A method for preparing a 37℃ Keminian reinforcement material includes the following steps: According to the formula, thermosetting phenolic resin, epoxy diluent and coupling agent are mixed to obtain resin liquid; then ultrafine calcium carbonate, nano silica, thixotropic agent and flame retardant are added in sequence and stirred evenly to obtain mixed liquid; composite curing agent is added to mixed liquid and vacuum degassing is performed to obtain 37℃ Keminan reinforcement material.

[0025] By adopting the above technical solution, the prepared 37℃ Kemin reinforcement material has excellent mechanical properties, bonding properties and dispersion stability, is suitable for underground construction scenarios without heating, and the preparation process is easy to industrialize and mass-produce, which can efficiently meet the reinforcement needs of fractured coal and rock masses.

[0026] In summary, this application has the following beneficial effects: 1. This application forms a composite curing agent by compounding a specific core and wall of 2-ethyl-4-methylimidazolium microcapsule curing agent with unencapsulated imidazolium. The process is controlled to make it stable at room temperature, and release the active components by breaking the cell wall at 37°C and synergizing with the unencapsulated imidazolium. This reduces the curing temperature of the phenolic resin-based reinforcement material to 37°C, which can be used in the mine without heating, adapting to construction needs. It can also penetrate the cracks in the coal and rock mass to form molecular-level chemical bonding, solving the problem of weak bonding and other reinforcement reliability issues of traditional inorganic chemiluminite materials.

[0027] 2. In the preparation of the composite curing agent of this application, an epoxy propylene block polyether emulsifier is introduced, which can effectively reduce the interfacial tension between 2-ethyl-4-methylimidazole and hydroxyethyl propylene glycol diglycidyl ether, promote the rapid and uniform mixing of the two, avoid local agglomeration, and improve the dispersion stability of the core mixture.

[0028] 3. The introduction of fumed silica during the preparation of the composite curing agent in this application can effectively prevent the mixture of capsule core and capsule wall from stratifying and settling in the suspension, improve the microcapsule encapsulation rate, and also adjust the viscosity of the suspension to adapt to the spray drying process, avoid atomization and particle size deviation problems, and finally obtain a microcapsule curing agent with uniform particle size and complete shell, further ensuring the consistency of the latency and low temperature response of the composite curing agent.

[0029] 4. While retaining the room temperature latency advantage of microcapsule curing agents, this application adds an appropriate amount of unencapsulated 2-ethyl-4-methylimidazolium and hydroxyethyl propylene glycol diglycidyl ether. The two work synergistically to reduce the crosslinking activation energy of phenolic resin, accelerate the curing rate at 37°C, and make the reaction more complete. This solves the problems of slow curing start-up and incomplete curing of microcapsule curing agents alone. It can also improve the crosslinking density and compatibility of the curing system, and ultimately enhance the mechanical, bonding strength and curing stability of the reinforced material, making it suitable for downhole 37°C construction without heating. Detailed Implementation

[0030] The present application will be further described in detail below with reference to the embodiments.

[0031] Unless otherwise specified, the raw materials used in the preparation examples, embodiments, and comparative examples of this application are all commercially available. Key technical indicators of all raw materials: The thermosetting phenolic resin is a linear phenolic resin with a number-average molecular weight of 800-1200, a solid content of 98±1%, and a phenolic hydroxyl content of 10-12wt%; the ultrafine calcium carbonate has a median particle size D50 of 2-5μm and a whiteness ≥5%; the nano-silica is hydrophilic with a specific surface area of ​​200-300m². 2 / g, average particle size 15-20nm; butyl / phenyl glycidyl ether epoxy value in epoxy diluent is 0.4-0.6eq / 100g; specific surface area of ​​hydrophobic fumed silica is 180-220m². 2 / g; Aluminum hydroxide is ultrafine, D50=1-3μm; melamine urate particle size ≤100 mesh, decomposition temperature ≥300℃; propylene oxide block polyether emulsifier is type F68, HLB value 18-19; polyvinyl alcohol is PVA1788, degree of alcoholysis 87-89%, viscosity 20-26mPa. s (25℃, 4% aqueous solution); Fumed silica is hydrophilic with a specific surface area of ​​150-200m². 2 / g.

[0032] Preparation Example 1 This preparation example discloses a method for preparing a composite curing agent, specifically including the following steps: (1) Mix 50g of 2-ethyl-4-methylimidazolium and 25g of hydroxyethyl propylene glycol diglycidyl ether at room temperature and at a speed of 300r / min for 15min until homogeneous to obtain a capsule core mixture; mix 20g of citric acid and 50g of polyurea-formaldehyde resin at room temperature and at a speed of 300r / min for 10min until homogeneous to obtain a capsule wall mixture. (2) 70g of capsule core mixture, 30g of capsule wall mixture and 130g of deionized water were stirred at 300r / min for 20min at room temperature to obtain a suspension; the suspension was sent into a centrifugal spray dryer and the process parameters were set as follows: inlet air temperature 135℃, outlet air temperature 70℃, atomization pressure 0.25MPa, feed rate 20mL / min and fan frequency 50Hz, and spray drying was carried out to obtain crude microcapsules; the crude microcapsules were sieved through an 80-mesh standard sieve, and the sieve material was placed in a 60℃ vacuum drying oven and dried at a vacuum degree of -0.08MPa for 2h to obtain microcapsule curing agent.

[0033] (3) Mix 75g of the above microcapsule curing agent and 25g of 2-ethyl-4-methylimidazole at room temperature and at a speed of 200r / min for 10min to obtain a composite curing agent.

[0034] Preparation Example 2 This preparation example is basically the same as Preparation Example 1, except that (1) 50g of 2-ethyl-4-methylimidazole and 25g of hydroxyethyl propylene glycol diglycidyl ether are stirred at 300r / min for 15min at room temperature, and then 0.75g of propylene oxide block polyether emulsifier is added. The temperature is adjusted to 35℃ and stirred at 400r / min for 20min. The mixture is homogeneous to obtain the capsule core mixture. 20g of citric acid and 50g of polyurea-formaldehyde resin are stirred at 300r / min for 10min at room temperature. The mixture is homogeneous to obtain the capsule wall mixture.

[0035] Preparation Example 3 This preparation example is basically the same as Preparation Example 1, except that (1) 50g of 2-ethyl-4-methylimidazole and 25g of hydroxyethyl propylene glycol diglycidyl ether are stirred at 300r / min for 15min at room temperature and mixed evenly to obtain a capsule core mixture; 20g of citric acid, 50g of polyurea-formaldehyde resin and 1.05g of polyvinyl alcohol are stirred at 300r / min for 15min at room temperature and mixed evenly to obtain a capsule wall mixture.

[0036] Preparation Example 4 This preparation example is basically the same as Preparation Example 1, except that (2) 70g of capsule core mixture, 30g of capsule wall mixture, 130g of deionized water and 0.5g of fumed silica are stirred at 400r / min for 30min at room temperature to obtain a suspension; the suspension is sent to a centrifugal spray dryer and the process parameters are set as follows: inlet air temperature 135℃, outlet air temperature 70℃, atomization pressure 0.25MPa, feed rate 20mL / min, fan frequency 50Hz, and spray drying is performed to obtain crude microcapsules; the crude microcapsules are sieved through an 80-mesh standard sieve, and the sieve material is placed in a 60℃ vacuum drying oven and dried at a vacuum degree of -0.08MPa for 2h to obtain microcapsule curing agent.

[0037] Preparation Example 5 This preparation example is basically the same as preparation example 1, except that (3) 50g of the above microcapsule curing agent, 25g of 2-ethyl-4-methylimidazole and 25g of hydroxyethyl propylene glycol diglycidyl ether are mixed at room temperature at a speed of 250r / min for 15min to obtain a composite curing agent.

[0038] Preparation Example 6 This preparation example discloses a method for preparing a composite curing agent, specifically including the following steps: (1) 40g of 2-ethyl-4-methylimidazole and 30g of hydroxyethyl propylene glycol diglycidyl ether were stirred at 300r / min for 15min at room temperature, and then 0.35g of propylene oxide block polyether emulsifier was added. The temperature was adjusted to 30℃ and stirred at 400r / min for 20min. The mixture was stirred evenly to obtain the capsule core mixture. 20g of citric acid, 40g of polyurea-formaldehyde resin and 0.6g of polyvinyl alcohol were stirred at 300r / min for 15min at room temperature. The mixture was stirred evenly to obtain the capsule wall mixture. (2) 65g of capsule core mixture, 35g of capsule wall mixture, 100g of deionized water and 0.3g of fumed silica were stirred at 400r / min for 30min at room temperature to obtain a suspension. The suspension was sent to a centrifugal spray dryer and the process parameters were set as follows: inlet air temperature 120℃, outlet air temperature 60℃, atomization pressure 0.2MPa, feed rate 20mL / min and fan frequency 50Hz. The microcapsule crude product was obtained by spray drying. The microcapsule crude product was sieved through an 80-mesh standard sieve. The sieve material was placed in a 60℃ vacuum drying oven and dried at a vacuum of -0.08MPa for 2h to obtain the microcapsule curing agent. (3) Mix 40g of the above microcapsule curing agent, 30g of 2-ethyl-4-methylimidazole and 30g of hydroxyethyl propylene glycol diglycidyl ether at room temperature for 15min at a speed of 250r / min to obtain a composite curing agent.

[0039] Preparation Example 7 This preparation example discloses a method for preparing a composite curing agent, specifically including the following steps: (1) 60g of 2-ethyl-4-methylimidazolium and 20g of hydroxyethyl propylene glycol diglycidyl ether were stirred at 300r / min for 15min at room temperature, and then 1.2g of propylene oxide block polyether emulsifier was added. The temperature was adjusted to 40℃ and stirred at 400r / min for 20min. The mixture was stirred evenly to obtain the capsule core mixture. 20g of citric acid, 60g of polyurea-formaldehyde resin and 1.6g of polyvinyl alcohol were stirred at 300r / min for 15min at room temperature. The mixture was stirred evenly to obtain the capsule wall mixture. (2) 75g of capsule core mixture, 25g of capsule wall mixture, 160g of deionized water and 0.8g of fumed silica were stirred at 400r / min for 30min at room temperature to obtain a suspension. The suspension was sent to a centrifugal spray dryer and the process parameters were set as follows: inlet air temperature 150℃, outlet air temperature 80℃, atomization pressure 0.3MPa, feed rate 20mL / min and fan frequency 50Hz. The microcapsule crude product was obtained by spray drying. The microcapsule crude product was sieved through an 80-mesh standard sieve. The sieve material was placed in a 60℃ vacuum drying oven and dried at a vacuum of -0.08MPa for 2h to obtain the microcapsule curing agent. (3) Mix 60g of the above microcapsule curing agent, 20g of 2-ethyl-4-methylimidazole and 20g of hydroxyethyl propylene glycol diglycidyl ether at room temperature for 15min at a speed of 250r / min to obtain a composite curing agent.

[0040] Example 1 This embodiment provides a 37℃ KH-Mian reinforcement material, comprising the following components: 55g thermosetting phenolic resin, 7g epoxy diluent (5g butyl glycidyl ether and 2g phenyl glycidyl ether), 4.5g composite curing agent (obtained from Preparation Example 1), 1g coupling agent (obtained by mixing 7.5mL ethanol with 2mL deionized water to obtain an ethanol solution, and then continuously stirring 0.5g KH-550, 0.5g KH-560 and 7g ethanol solution at 32℃ and 200rpm for 20min), and 22g ultrafine calcium carbonate. 2g of nano-silica, 0.5g of thixotropic agent (0.3g of hydrophobic fumed silica and 0.2g of modified organobentonite, wherein the modified organobentonite is a mixture of 1g of sodium bentonite and 10g of 4wt% hexadecyltrimethylammonium chloride aqueous solution, the pH of the system is adjusted to 8, stirred at 400rpm for 45min at 35℃, aged for 2h, then the solid and liquid are separated, washed with deionized water until no chloride ions are present, dried at 90℃ for 6h, and then pulverized and passed through a 200-mesh sieve) and 9g of flame retardant (7g of aluminum hydroxide and 2g of melamine urate). This embodiment also provides a method for preparing the above-mentioned 37℃ Keminian reinforcement material, including the following steps: According to the above formula, weigh the thermosetting phenolic resin and add it to the reaction vessel. Turn on the stirring, adjust the speed to 400 rpm, and add the epoxy diluent at a temperature of 40°C. Continue stirring for 15 minutes, then add the coupling agent and continue stirring for 10 minutes to obtain the resin solution. Keep the reactor temperature constant at 40℃, adjust the rotation speed to 800 rpm, and add ultrafine calcium carbonate, nano silica, thixotropic agent and flame retardant to the resin liquid in sequence. Stir continuously for 8 minutes after each addition of raw material to obtain a mixture. Cool the mixture to 25°C, adjust the rotation speed to 200 rpm, add the composite curing agent, stir continuously for 10 min, and then perform vacuum degassing treatment, controlling the vacuum degree to -0.08 MPa and degassing for 5 min to obtain the 37°C Kemian reinforcement material.

[0041] Example 2 This embodiment is basically the same as Example 1, except that the composite curing agent is the one obtained in Preparation Example 2.

[0042] Example 3 This embodiment is basically the same as Example 1, except that the composite curing agent is the one obtained in Preparation Example 3.

[0043] Example 4 This embodiment is basically the same as Example 1, except that the composite curing agent is the one obtained in Preparation Example 4.

[0044] Example 5 This embodiment is basically the same as Example 1, except that the composite curing agent is the one obtained in Preparation Example 5.

[0045] Example 6 This embodiment is basically the same as Embodiment 1, except that this embodiment provides a 37°C KH-Mian reinforcement material, comprising the following components: 45g of thermosetting phenolic resin, 3g of epoxy diluent (2g of butyl glycidyl ether and 1g of phenyl glycidyl ether), 3g of composite curing agent (obtained from Preparation Example 6), and 0.5g of coupling agent (obtained by mixing 3mL of ethanol with 1mL of deionized water to obtain an ethanol solution, and continuously stirring 0.25g of KH-550, 0.25g of KH-560 and 3.5g of ethanol solution at 32°C at 200rpm for 20min). 15g of ultrafine calcium carbonate, 1g of nano silica, 0.3g of thixotropic agent (0.15g of hydrophobic fumed silica and 0.15g of modified organobentonite, wherein the modified organobentonite is 1g of sodium-based bentonite mixed with 10g of 4wt% hexadecyltrimethylammonium chloride aqueous solution, the pH of the system is adjusted to 8, stirred at 400rpm for 45min at 35℃, aged for 2h, then the solid and liquid are separated, washed with deionized water until no chloride ions are present, dried at 90℃ for 6h, and then pulverized and passed through a 200-mesh sieve) and 5g of flame retardant (4g of aluminum hydroxide and 1g of melamine urate).

[0046] Example 7 This embodiment is basically the same as Embodiment 1, except that this embodiment provides a 37℃ KH-550 reinforcement material, comprising the following components: 65g of thermosetting phenolic resin, 8g of epoxy diluent (6g of butyl glycidyl ether and 2g of phenyl glycidyl ether), 4.5g of composite curing agent (obtained from Preparation Example 7), and 1.5g of coupling agent (obtained by mixing 15mL of ethanol with 4mL of deionized water to obtain an ethanol solution, and continuously stirring 0.75g of KH-550, 0.75g of KH-560 and 14g of ethanol solution at 32℃ and 200rpm for 20min). The mixture consists of 30g of ultrafine calcium carbonate, 3g of nano silica, 1g of thixotropic agent (0.67g of hydrophobic fumed silica and 0.33g of modified organobentonite, wherein the modified organobentonite is 1g of sodium-based bentonite mixed with 10g of 4wt% hexadecyltrimethylammonium chloride aqueous solution, the pH of the system is adjusted to 8, stirred at 400rpm for 45min at 35℃, aged for 2h, then solid-liquid separation, washed with deionized water until no chloride ions are present, dried at 90℃ for 6h, and then pulverized and passed through a 200-mesh sieve), and 12g of flame retardant (9g of aluminum hydroxide and 3g of melamine urate).

[0047] Comparative Example 1 This comparative example provides a reinforcing material. Mixing 575g of anhydrous calcium aluminum sulfate powder, 70g of gypsum powder, and 265g of silicate cement at room temperature forms a mixed ash (A). Adding water and mixing further produces slurry (A), with a water-cement ratio of 0.3:1. Mixing 690g of slag silicate cement, 285g of ultrafine cement, and 1g of retarder at room temperature forms mixed ash (B). Adding water and mixing further produces slurry (B), with a water-cement ratio of 0.3:1. The reinforcing material is obtained by mixing slurry (A) and slurry (B) at a mass ratio of 1:1.

[0048] Comparative Example 2 This comparative example is basically the same as Example 1, except that the composite curing agent is the microcapsule curing agent obtained in Preparation Example 1.

[0049] Comparative Example 3 This comparative example is basically the same as Example 1, except that the composite curing agent is 2-ethyl-4-methylimidazole.

[0050] Performance testing Curing performance at 37℃: The ambient temperature was controlled at 37±1℃ using a constant temperature and humidity chamber. The prepared reinforcement material samples (50mm×50mm×50mm) were placed in the chamber, and the complete curing time was recorded. For Examples 1-7 and Comparative Examples 2-3, the criteria for complete curing were no indentation when pressed with a finger and a Shore hardness ≥85D. For Comparative Example 1, the criteria for complete curing was the final setting time (tested using a Vicat apparatus, conforming to GB / T 1346-2011 "Standard Consistency Water Requirement, Setting Time and Soundness Test Methods for Cement"). The test results are recorded in Table 1.

[0051] Bond strength: Referring to the "Technical Conditions for Reinforcing Materials for Coal Mines" (MT / T1104-2011), the interfacial bond strength between the reinforcing material and the coal and rock mass (a typical crushed coal sample from underground was selected and ground flat) was tested using a universal testing machine. The test rate was 1 mm / min. The ratio of the maximum load at fracture to the bonded area of ​​the reinforcing materials prepared in Examples 1-7 and Comparative Examples 1-3 was taken as the bond strength. The test results are recorded in Table 1.

[0052] Permeability performance: Using a simulated coal and rock mass fracture device (fracture width 0.1-0.5mm), the permeability depth of the reinforcement materials prepared in Examples 1-7 and Comparative Examples 1-3 was tested under normal temperature and pressure conditions. A permeability depth ≥50mm meets the requirements for permeability in downhole micro-fractures. The test results are recorded in Table 1.

[0053] Stability at room temperature: The reinforcing materials prepared in Examples 1-7 and Comparative Examples 1-3 were sealed and placed in a dry and ventilated environment at 25℃±2℃. The state of the system was observed regularly (whether there was stratification, precipitation, or clumping), and the shelf life was recorded (the presence of stratification, precipitation, or clumping indicates failure).

[0054] Table 1. Performance test data of the 37℃ Keminian reinforcement material in Examples 1-7 and Comparative Examples 1-3.

[0055] Referring to Table 1, and combining Example 1 and Comparative Example 1, it can be seen that in terms of curing performance at 37℃, Example 1 can achieve complete curing in 4 hours without additional heating, and the curing speed is close to that of Comparative Example 1, fully meeting the progress requirements of underground on-site construction. In terms of bonding strength, the interface between Example 1 and the coal and rock mass is more tightly and firmly bonded, and the bonding effect is significantly better than that of Comparative Example 1, effectively solving the problem of weak physical bonding of traditional inorganic reinforcement materials represented by Comparative Example 1. In terms of penetration performance, Example 1 can effectively penetrate into the micro-fractures of the coal and rock mass, and its penetration capacity is significantly better than that of Comparative Example 1, which can achieve comprehensive coverage and reinforcement of broken coal and rock mass, further ensuring the integrity and reliability of the underground support system. In terms of storage stability, the shelf life of Example 1 is much longer than that of Comparative Example 1, which can achieve long-term storage and transportation, and has the feasibility of industrial mass production and on-site application. In contrast, Comparative Example 1 has poor storage stability and is prone to failure, which cannot meet the storage requirements of actual projects.

[0056] Referring to Table 1, and combining Example 1 and Comparative Examples 2-3, it can be seen that, in terms of curing performance at 37℃, Example 1 has a better curing efficiency than Comparative Example 2, and its curing speed is more suitable for the needs of underground on-site construction. It also avoids the problem of Comparative Example 3 having an excessively fast curing speed and insufficient applicable period, thus failing to meet the construction requirements. Regarding bonding strength, Example 1 shows better interfacial bonding with the coal and rock mass than Comparative Examples 2 and 3, forming a stronger bond and ensuring reinforcement reliability. In terms of permeability, Example 1 has better permeability than Comparative Example 2 and is close to that of Comparative Example 3. In terms of storage… In terms of stability, Example 1 and Comparative Example 2 have similar shelf life and good room temperature storage stability, while Comparative Example 3 has an extremely short shelf life and is prone to premature curing and failure at room temperature, making it unsuitable for long-term storage and industrial application. Considering the overall curing performance, bonding effect and storage stability, Example 1 has better overall performance, which fully demonstrates the rationality of the composite curing agent compounding scheme of this application. It effectively solves the defects of insufficient curing efficiency of single microcapsule curing agent and short applicable period and unstable storage of single uncoated curing agent, and is more suitable for the actual needs of downhole 37°C unheated construction scenarios.

[0057] Referring to Table 1 and combining Examples 1 and 2, it can be seen that, in terms of curing performance at 37℃, Example 2, relying on the composite curing agent prepared with the addition of propylene oxide block polyether emulsifier, has a better curing efficiency than Example 1, and its curing speed is more suitable for the needs of underground on-site construction. In terms of bonding strength, Example 2 has a better interface bonding effect with the coal and rock mass than Example 1, forming a stronger bond and ensuring the reliability of reinforcement. In terms of penetration performance, Example 2 also has a better penetration capacity than Example 1, penetrating deeper into the micro-fractures of the coal and rock mass. In terms of storage stability, Example 2 has a slightly longer shelf life than Example 1, further improving the storage and transportation reliability of the material. This fully demonstrates the necessity and superiority of introducing propylene oxide block polyether emulsifier in the preparation process of the composite curing agent in this application. This technical feature significantly improves the mixing uniformity and dispersion stability of the core mixture, thereby synergistically optimizing the overall performance of the reinforcement material in terms of curing, bonding, penetration, and storage stability, making it more suitable for the actual needs of underground 37℃ unheated construction scenarios.

[0058] Referring to Table 1 and combining Examples 1 and 3, it can be seen that the overall performance of Example 3 is superior to that of Example 1. In terms of curing performance at 37℃, Example 3 exhibits better curing efficiency and a curing speed that better matches the pace of underground construction. Regarding bonding strength, Example 3 demonstrates a stronger interface bond with the coal and rock mass, further enhancing the reliability of the reinforcement. In terms of penetration performance, Example 3 also shows improved penetration capacity, allowing for more thorough penetration into the micro-fractures of the coal and rock mass, achieving a more comprehensive reinforcement effect. Regarding storage stability, the shelf life of Example 3 is consistent with that of Example 2, and superior to that of Example 1, improving the long-term storage feasibility of the material. This difference stems from the addition of polyvinyl alcohol to the capsule wall mixture during the preparation of the composite curing agent in Example 3. This component effectively improves the dispersion uniformity of organic acids in the polyurea-formaldehyde resin wall material, optimizes the film-forming properties of the capsule wall, makes the microcapsule structure denser, and its temperature-sensitive response more precise. This, in turn, synergistically improves the various core performance characteristics and storage stability of the reinforcement material, making it more suitable for the actual needs of underground construction scenarios at 37℃ without heating.

[0059] Referring to Table 1 and combining Examples 1 and 4, it can be seen that the overall performance of Example 4 is superior to that of Example 1. In terms of curing performance at 37℃, Example 4 exhibits higher curing efficiency and a curing speed that better meets the needs of underground on-site construction, effectively improving construction efficiency. Regarding bonding strength, Example 4 shows a tighter interface bond with the coal and rock mass, further enhancing the stability and reliability of the reinforcement. In terms of penetration performance, Example 4 also demonstrates significantly improved penetration ability, allowing for deeper penetration into the micro-fractures of the coal and rock mass, achieving more comprehensive and effective reinforcement. Regarding storage stability, Example 4 has a longer shelf life than Example 1, better meeting the storage and transportation needs of industrial production. The core reason for this performance difference is that Example 4 added fumed silica to the suspension during the preparation of the composite curing agent. This component effectively prevents the stratification and sedimentation of the core mixture and the wall mixture, improves the encapsulation rate and particle size uniformity of the microcapsules, optimizes the latency and low-temperature response consistency of the composite curing agent, and thus synergistically improves the core performance and storage stability of the reinforcement material, making it more suitable for the actual needs of underground construction scenarios at 37℃ without heating.

[0060] Referring to Table 1 and combining Examples 1 and 5, it can be seen that the overall performance of Example 5 is superior to that of Example 1. In terms of curing performance at 37℃, Example 5 has better curing efficiency and a curing speed that is more suitable for the pace of on-site construction in the mine, thus better matching the construction progress requirements. In terms of bonding strength, Example 5 has a stronger interface bond with the coal and rock mass, further improving the reliability of the reinforcement system and effectively avoiding interface debonding problems. In terms of penetration performance, the penetration capacity of Example 5 is also improved, allowing it to penetrate more fully into the micro-fractures of the coal and rock mass, achieving comprehensive reinforcement of the fractured coal and rock mass. In terms of storage stability, the shelf life of Example 5 is consistent with that of Example 4, which is better than that of Example 1, ensuring the stability and practicality of the material during long-term storage. This performance difference stems from the optimization of the composite curing agent formulation in Example 5. Based on the microencapsulated curing agent, an appropriate amount of unencapsulated 2-ethyl-4-methylimidazolium and hydroxyethyl propylene glycol diglycidyl ether were added. The synergistic effect of the two further reduced the crosslinking activation energy of the phenolic resin, accelerated the curing rate, improved the curing sufficiency, and enhanced the crosslinking density and compatibility of the curing system. This, in turn, synergistically optimized the core performance and storage stability of the reinforcement material, making it more suitable for the actual needs of downhole 37°C unheated construction scenarios.

[0061] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A 37°C Kevlar® reinforcement material, characterized in that, The raw materials include the following parts by weight: 45-65 parts thermosetting phenolic resin, 3-8 parts epoxy diluent, 3-6 parts composite curing agent, 0.5-1.5 parts coupling agent, 15-30 parts ultrafine calcium carbonate, 1-3 parts nano silica, 0.3-1 parts thixotropic agent and 5-12 parts flame retardant. The preparation method of the composite curing agent includes the following steps: (1) Mix 2-ethyl-4-methylimidazolium and hydroxyethyl propylene glycol diglycidyl ether in a mass ratio of (4-6):(2-3) to obtain a core mixture; mix citric acid and polyurea-formaldehyde resin wall material in a mass ratio of 1:(2-3) to obtain a wall mixture; (2) Mix 65-75 parts by weight of the capsule core mixture, 25-35 parts by weight of the capsule wall mixture and 100-160 parts by weight of deionized water to form a suspension; spray dry the suspension under the conditions of inlet air temperature of 120-150℃, outlet air temperature of 60-80℃ and atomization pressure of 0.2-0.3MPa to form microcapsules; sieve and dry the microcapsules to obtain a microcapsule curing agent; (3) Mix 70-80 parts by weight of microcapsule curing agent with 20-30 parts by weight of 2-ethyl-4-methylimidazole to obtain a composite curing agent.

2. The 37 °C Kevlar® reinforcement material of claim 1, wherein, In step (1), 2-ethyl-4-methylimidazole and hydroxyethyl propylene glycol diglycidyl ether are mixed in a mass ratio of (4-6):(2-3), and then propylene oxide block polyether emulsifier is added. The mixture is stirred at 30-40°C for 10-20 minutes to obtain a core mixture. The amount of propylene oxide block polyether emulsifier added is 0.5%-1.5% of the total mass of 2-ethyl-4-methylimidazole and hydroxyethyl propylene glycol diglycidyl ether.

3. The 37℃ Kemin reinforcement material according to claim 1, characterized in that, In step (1), citric acid and polyurea-formaldehyde resin wall material are mixed in a mass ratio of 1:(2-3), and then polyvinyl alcohol is added to mix to obtain a capsule wall mixture; the amount of polyvinyl alcohol added is 1%-2% of the total mass of citric acid and polyurea-formaldehyde resin wall material.

4. The 37℃ Kemin reinforcement material according to claim 1, characterized in that, Step (2) Mix 65-75 parts by weight of the capsule core mixture, 25-35 parts by weight of the capsule wall mixture, 100-160 parts by weight of deionized water and 0.3-0.8 parts by weight of fumed silica to form a suspension; spray dry the suspension under the conditions of inlet air temperature of 120-150℃, outlet air temperature of 60-80℃ and atomization pressure of 0.2-0.3MPa to form microcapsules; sieve and dry the microcapsules to obtain a microcapsule curing agent.

5. The 37℃ Kemin reinforcement material according to claim 1, characterized in that, Step (3) Mix 40-60 parts by weight of microcapsule curing agent, 20-30 parts by weight of 2-ethyl-4-methylimidazole and 20-30 parts by weight of hydroxyethyl propylene glycol diglycidyl ether to obtain composite curing agent.

6. The 37℃ Kemin reinforcement material according to claim 1, characterized in that, The epoxy diluent is a mixture of butyl glycidyl ether and phenyl glycidyl ether in a mass ratio of (2-3):

1.

7. The 37℃ Kemin reinforcement material according to claim 1, characterized in that, The coupling agent is prepared by blending KH-550, KH-560 and an ethanol solution, wherein the mass ratio of KH-550 to KH-560 is 1:

1.

8. The 37℃ Kemin reinforcement material according to claim 1, characterized in that, The thixotropic agent is a mixture of hydrophobic fumed silica and modified organobentonite in a mass ratio of (1-2):1; the modified organobentonite is obtained by modifying sodium-based bentonite with an aqueous solution of hexadecyltrimethylammonium chloride.

9. The 37℃ Kemin reinforcement material according to claim 1, characterized in that, The flame retardant is a mixture of aluminum hydroxide and melamine urate in a mass ratio of (3-4):

1.

10. A method for preparing a 37°C Keminian-reinforced material as described in any one of claims 1-9, characterized in that, Includes the following steps: According to the formula, thermosetting phenolic resin, epoxy diluent and coupling agent are mixed to obtain resin liquid; then ultrafine calcium carbonate, nano silica, thixotropic agent and flame retardant are added in sequence and stirred evenly to obtain mixed liquid; composite curing agent is added to mixed liquid and vacuum degassing is performed to obtain 37℃ Keminan reinforcement material.

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