Mine supporting material interface reinforcing agent, its preparation method and application

Abstract

The present application relates to a kind of mine supporting material interface reinforcing agent and its preparation method and application, the reinforcing agent includes the following components: phosphonic acid group functionalized polycarboxylic acid polymer, polymer toughening component, silane coupling reinforcing agent, nano reinforcing material and deionized water.The preparation method includes phosphonic acid group functionalized polycarboxylic acid polymer preparation and composite reinforcing system preparation.The present application is designed by molecular structure, and carboxyl in phosphonic acid group functionalized polycarboxylic acid polymer and phosphonic group produce synergies, form coordination bond with cement hydration product and metal ion in mineral interface, improve the adsorption anchoring capacity of organic component on inorganic interface;Silane coupling reinforcing effect and nano reinforcing effect are combined simultaneously, and stable interface connection structure is built between organic polymer and mineral base material, so that the interface bonding performance of mine supporting material, early bearing capacity and anti-permeability durability are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of building material admixtures, specifically to an interface reinforcing agent for mine support materials, its preparation method, and its application. Background Technology

[0002] As coal and metal mining in my country continues to deepen, the pressure on the surrounding rock underground is constantly increasing, and complex environmental problems such as fractured surrounding rock, high ground stress, high salt erosion, and groundwater seepage are becoming increasingly prominent. At the same time, the promotion and application of rapid tunneling and continuous construction technologies have placed higher demands on mine support materials, requiring them to have rapid load-bearing capacity, high early strength, excellent interfacial bonding performance, and long-term durability.

[0003] Currently, cement-based cementitious materials still dominate mine support materials. However, traditional cement-based support materials suffer from slow early strength development, insufficient bonding with the surrounding rock interface, and decreased durability in complex environments. To address these issues, existing technologies primarily improve the situation by optimizing the cementitious system or introducing functional components. For example, patent CN118955813A designs a low-temperature early-strength water-reducing agent to accelerate the cement hydration process and improve short-age strength; patent CN119349966A uses a sulfoaluminate cement system, leveraging its rapid-hardening and early-strength characteristics to improve early load-bearing capacity; and patent CN119100661A improves material toughness and interlayer performance by compounding polymers, silica fume, and polycarboxylate water-reducing agents. However, these technologies mainly focus on optimizing the internal structure of the cement matrix or improving single properties, and are insufficient in addressing the interfacial chemical bonding between the support material and the surrounding rock, as well as the synergistic enhancement of multiple properties.

[0004] Polycarboxylate polymers possess the advantages of designable molecular structures and easily tunable functional groups. Their carboxyl groups, polyether side chains, and functionalized groups can interact with cement particles, hydration products, and mineral interfaces through adsorption and complexation. By introducing functional groups with interfacial anchoring capabilities, the bonding between the polymer and the inorganic mineral interface can be enhanced, achieving a synergistic effect of regulating cement hydration, strengthening interfacial adhesion, and improving long-term durability.

[0005] Therefore, developing an interface reinforcement material for mine support based on functionalized polycarboxylic acid molecules is of great significance for improving the support performance of deep mines and ensuring the long-term stable operation of roadways. Summary of the Invention

[0006] To address the problems in related technologies, this invention proposes an interface reinforcing agent for mine support materials, its preparation method, and its application, in order to overcome the aforementioned technical problems existing in the existing related technologies. The purpose of this invention is to prepare phosphate-functionalized polycarboxylic acid polymers through molecular structure design, and further release them with polymer toughening components, silane coupling reinforcing agents, and nano-reinforcing materials to construct a composite bonding and reinforcing system with synergistic effects of "molecular adsorption-interface anchoring-structural reinforcement".

[0007] When the reinforcing agent of this invention is applied to mine support materials, it first adsorbs onto the cement particles and mineral interfaces through the active functional groups such as carboxyl and phosphate groups in the phosphate-functionalized polycarboxylate polymer, improving the dispersion stability of organic components in the inorganic cementitious system. The phosphate groups have a high metal ion coordination ability and can enhance the binding stability between the phosphate-functionalized polycarboxylate polymer chains and cement hydration products through PO-Ca and PO-Al interfacial interactions, transforming the phosphate-functionalized polycarboxylate polymer molecules from a traditional physical adsorption mode to a chemical anchoring mode. Subsequently, the silane coupling reinforcing agent undergoes hydrolysis to form a reactive silanol structure, which can further condense with hydroxyl groups on the mineral surface, establishing a stable interfacial connection between the organic polymer and inorganic minerals. Simultaneously, the nano-reinforcing material promotes the generation of hydration products and optimizes the pore structure through nucleation-induced effects and nano-filling effects, ultimately improving the interfacial bonding strength, early load-bearing capacity, and long-term service stability of the mine support material.

[0008] The reinforcing agent preparation process described in this invention is simple, the raw materials are widely available, and the cost is controllable. It is applicable to the fields of mine support materials, cement-based grouting materials, shotcrete, and high-performance cementitious materials.

[0009] During the research process, the inventors of this invention discovered that traditional polycarboxylate polymers are mainly used to improve the dispersion performance of cement particles. Their molecular structure lacks functional groups that can form stable connections with hydration products. Therefore, in the application of mine support materials, they mainly rely on physical adsorption to achieve reinforcement, and their interfacial bonding performance is insufficient under long-term service conditions.

[0010] To address the aforementioned problems, this invention modulates the molecular structure of phosphate-functionalized polycarboxylic acid polymers by introducing phosphate-functionalized acrylic acid functional monomers into the phosphate-functionalized polycarboxylic acid polymer molecular chains. This allows the phosphate-functionalized polycarboxylic acid polymer molecular chains to simultaneously possess carboxyl groups, polyether side chains, and phosphate groups, thereby constructing functionalized polycarboxylic acid molecules with interfacial adsorption and chemical anchoring effects.

[0011] Among them, the carboxyl group can complex with Ca²⁺ on the surface of cement particles and in hydration products, thereby improving the adsorption capacity of phosphate-functionalized polycarboxylate polymer molecules on mineral surfaces; the phosphate group can form stable coordination structures with Ca²⁺, Al³⁺, etc., thereby improving the interfacial bonding strength between phosphate-functionalized polycarboxylate polymer molecules and cement hydration products; and the polyether side chain can improve the dispersion performance of reinforcing components in the cementitious system and improve the material's workability.

[0012] Furthermore, by introducing silane coupling reinforcing agents, the reinforcing system is made capable of interfacial chemical coupling. After hydrolysis, the silane groups form silanol structures, which can undergo condensation reactions with hydroxyl groups on the mineral surface, establishing a stable connection between the organic polymer and the inorganic substrate, thereby improving the tensile strength and durability of the interfacial region.

[0013] To achieve the above objectives, the present invention provides the following technical solution: an interface reinforcing agent for mine support materials, comprising the following components by mass percentage: The composition consists of 30-60% phosphate-functionalized polycarboxylic acid polymer, 10-30% polymer toughening component, 1-8% silane coupling reinforcing agent, 5-20% nano-reinforcing material, and deionized water. The phosphoric acid-functionalized polycarboxylate polymer is prepared by free radical copolymerization of unsaturated polyether monomers, unsaturated carboxylic acid monomers, and phosphoric acid-based acrylic acid functional monomers. Specifically, a multi-scale interface reinforcement system is constructed through the synergistic effect of the phosphoric acid-functionalized polycarboxylate polymer, polymer toughening components, silane functional reinforcing agents, and nano-reinforcing materials.

[0014] Preferably, the phosphate-functionalized polycarboxylic acid polymer molecular chain simultaneously contains carboxyl groups, polyether side chains, and phosphate groups; the phosphate groups are used to coordinate with metal ions in cement hydration products to enhance the bonding between polymer molecules and mineral interfaces.

[0015] Preferably, the unsaturated polyether monomer is one or more of methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, isobutylenyl polyoxyethylene ether, and vinyl polyoxyethylene ether; the unsaturated carboxylic acid monomer is one or more of acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid; and the phosphate-based acrylic functional monomer is one or more of phosphate methacrylate, phosphate acrylate, and vinyl phosphate.

[0016] Preferably, the molar ratio of the unsaturated polyether monomer, the unsaturated carboxylic acid monomer, and the phosphate-based acrylic acid functional monomer is 5–20:1:0.05–0.5.

[0017] Preferably, the polymer toughening component is one or more combinations of redispersible latex powder, acrylic emulsion, styrene-acrylic emulsion, styrene-butadiene emulsion, and ethylene-vinyl acetate emulsion.

[0018] Preferably, the silane coupling enhancer is one or more combinations of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and vinyltriethoxysilane.

[0019] Preferably, the nano-reinforcing material is one or more combinations of nano-silica, nano-hydrated calcium silicate, nano-alumina, nano-calcium carbonate, nano-montmorillonite, and nano-silicate.

[0020] To achieve the above objectives, the present invention also provides the following technical solution: A method for preparing an interface reinforcing agent for mine support materials includes the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Unsaturated polyether monomers, chain transfer agents, reducing agents and catalysts are added to deionized water and stirred until homogeneous; then, unsaturated carboxylic acid monomers, phosphate-based acrylic functional monomers and oxidants are simultaneously added dropwise to the reaction system, and a free radical copolymerization reaction is carried out at 20~45℃; after the reaction is completed, the phosphate-functionalized polycarboxylic acid polymer is obtained after neutralization treatment. Step S2, preparation of composite reinforcement system: Add polymer toughening component, silane coupling reinforcement agent and nano-reinforcing material to the phosphate functionalized polycarboxylic acid polymer obtained in step S1, and perform mechanical stirring to make the components uniformly composite, so as to obtain the interface reinforcement agent for mine support materials.

[0021] To achieve the above objectives, the present invention also provides the following technical solution: An application of an interface reinforcing agent for mine support materials is disclosed, wherein the interface reinforcing agent is applied to at least one of mine support materials, cement-based grouting materials, shotcrete, anchoring mortar, and high-strength repair materials. Specifically, it is used to improve the interfacial bonding performance, early load-bearing capacity, impermeability, and structural stability of mine support materials.

[0022] Preferably, the mine support material includes a cementitious material, which is one or more combinations of ordinary Portland cement, sulfoaluminate cement, ferroaluminate cement, mineral powder, and fly ash. The amount of the interface reinforcing agent added to the mine support material is 0.5-5% of the mass of the cementitious material. Specifically, in use, the reinforcing agent is added to the mine support material system at 0.5-5.0% of the total mass of the cementitious material. Through polycarboxylic acid molecular adsorption, phosphate group interface anchoring, silane coupling reinforcement, and nano-filling reinforcement, the bonding performance between the material and the surrounding rock or substrate is improved.

[0023] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention is a mine support material interface enhancer and its preparation method and application. By introducing phosphate-based acrylic acid functional monomers, the functional design of polycarboxylic acid molecules is realized, which transforms it from a traditional particulate dispersion polymer into a multifunctional enhancer molecule with dispersion regulation, interface adsorption and chemical anchoring functions, effectively improving the interface bonding performance of support materials. (2) This invention is a mine support material interface enhancer, its preparation method and application. The carboxyl and phosphate groups in the phosphate-functionalized polycarboxylic acid polymer molecular chain can form coordination with mineral ions such as Ca²⁺ and Al³⁺, thereby improving the bonding strength of the phosphate-functionalized polycarboxylic acid polymer at the cement hydration product and mineral interface. (3) This invention is a mine support material interface reinforcing agent and its preparation method and application. By setting silane functional reinforcing agent, chemical connection can be formed between organic polymer and inorganic mineral, improving interface stability and reducing interface defects. By setting nano reinforcing material, crystal nucleation induction and nano filling can be played, promoting the generation of hydration products, optimizing pore structure, and improving the early strength and long-term durability of the material. (4) This invention is a mine support material interface reinforcing agent, its preparation method and application. By setting the reinforcing agent, it is applicable to ordinary silicate cement, sulfoaluminate cement, ferroaluminate cement and mine filling cementitious material system. It can significantly improve the bonding strength, compressive strength and crack resistance of the support material. At the same time, the preparation method is simple, the raw material cost is controllable, and it is suitable for industrial production and promotion and application in mining engineering. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the synthetic route for the phosphoric acid-functionalized polycarboxylic acid polymer in the reinforcing agent of this invention; Figure 2 This is a schematic diagram illustrating the function of the reinforcing agent of the present invention; Figure 3 This is a GPC test diagram of the phosphoric acid functionalized polycarboxylate polymer in the reinforcing agent of this invention; Figure 4 This is a diagram showing the on-site construction effect of Example 1. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] Example 1 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Vinyl polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Acrylic acid (5.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add 20 g of acrylic emulsion to 100 g of the phosphate-functionalized polycarboxylic acid polymer obtained in step S1, stir evenly to make the toughening component of the polymer uniformly dispersed in the polycarboxylic acid system; then add 3.0 g of γ-aminopropyltriethoxysilane and 10.0 g of nano-hydrated calcium silicate, stir and react at 40°C for 1 h, and obtain the interface reinforcement agent for mine support materials after high-speed stirring and dispersion.

[0027] Example 2 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Isoprene alcohol polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Acrylic acid (5.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add 20 g of acrylic emulsion to 100 g of the phosphate-functionalized polycarboxylic acid polymer obtained in step S1, stir evenly to make the toughening component of the polymer uniformly dispersed in the polycarboxylic acid system; then add 3.0 g of γ-aminopropyltriethoxysilane and 10.0 g of nano-hydrated calcium silicate, stir and react at 40°C for 1 h, and obtain the interface reinforcement agent for mine support materials after high-speed stirring and dispersion.

[0028] Example 3 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Isobutylene polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Acrylic acid (5.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add 20 g of acrylic emulsion to 100 g of the phosphate-functionalized polycarboxylic acid polymer obtained in step S1, stir evenly to make the toughening component of the polymer uniformly dispersed in the polycarboxylic acid system; then add 3.0 g of γ-aminopropyltriethoxysilane and 10.0 g of nano-hydrated calcium silicate, stir and react at 40°C for 1 h, and obtain the interface reinforcement agent for mine support materials after high-speed stirring and dispersion.

[0029] Example 4 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Vinyl polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Then, methacrylic acid (5.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add 20 g of acrylic emulsion to 100 g of the phosphate-functionalized polycarboxylic acid polymer obtained in step S1, stir evenly to make the toughening component of the polymer uniformly dispersed in the polycarboxylic acid system; then add 3.0 g of γ-aminopropyltriethoxysilane and 10.0 g of nano-hydrated calcium silicate, stir and react at 40°C for 1 h, and obtain the interface reinforcement agent for mine support materials after high-speed stirring and dispersion.

[0030] Example 5 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Vinyl polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Maleic anhydride (5.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add 20 g of acrylic emulsion to 100 g of the phosphate-functionalized polycarboxylic acid polymer obtained in step S1, stir evenly to make the toughening component of the polymer uniformly dispersed in the polycarboxylic acid system; then add 3.0 g of γ-aminopropyltriethoxysilane and 10.0 g of nano-hydrated calcium silicate, stir and react at 40°C for 1 h, and obtain the interface reinforcement agent for mine support materials after high-speed stirring and dispersion.

[0031] Example 6 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Vinyl polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Maleic anhydride (5.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add styrene-butadiene emulsion (20 g) to the phosphate-functionalized polycarboxylic acid polymer (100 g) obtained in step S1, stir evenly to make the toughening component of the polymer uniformly dispersed in the polycarboxylic acid system; then add γ-aminopropyltriethoxysilane (3.0 g) and nano-hydrated calcium silicate (10.0 g), stir and react at 40℃ for 1 h, and obtain the interface reinforcement agent for mine support materials after high-speed stirring and dispersion.

[0032] Example 7 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Vinyl polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Acrylic acid (5.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add 20 g of acrylic emulsion to 100 g of the phosphate-functionalized polycarboxylic acid polymer obtained in step S1, stir evenly to make the toughening component of the polymer uniformly dispersed in the polycarboxylic acid system; then add 3.0 g of γ-methacryloyloxypropyltrimethoxysilane and 10.0 g of nano-hydrated calcium silicate, stir and react at 40°C for 1 h, and obtain the interface reinforcement agent for mine support materials after high-speed stirring and dispersion.

[0033] Example 8 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Vinyl polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Acrylic acid (4.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add 20 g of acrylic emulsion to 100 g of the phosphate-functionalized polycarboxylic acid polymer obtained in step S1, stir evenly to make the toughening component of the polymer uniformly dispersed in the polycarboxylic acid system; then add 3.0 g of γ-aminopropyltriethoxysilane and 10.0 g of nano-hydrated calcium silicate, stir and react at 40°C for 1 h, and obtain the interface reinforcement agent for mine support materials after high-speed stirring and dispersion.

[0034] Comparative Example 1 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of Phosphoric Acid Functionalized Polycarboxylate Polymer: Vinyl polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred until homogeneous. Acrylic acid (5.0 g) and deionized water (4.0 mL) were then mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and simultaneously added dropwise to the reaction solution along with the monomer mixture. The addition time was controlled at 1.5 h, and the reaction temperature was 30 °C. After the addition was completed, the reaction was maintained at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphoric acid functionalized polycarboxylate polymer. Step S2, preparation of composite reinforcement system: Add acrylic emulsion (20 g) to the phosphate-functionalized polycarboxylic acid polymer solution (100 g) obtained in step S1, stir evenly to make the polymer toughening component uniformly dispersed in the polycarboxylic acid system; then add γ-aminopropyltriethoxysilane (3.0 g) and nano-hydrated calcium silicate (10.0 g), stir and react at 40℃ for 1 h, and obtain Comparative Example 1 after high-speed stirring and dispersion.

[0035] Comparative Example 2 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Vinyl polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Acrylic acid (4.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add acrylic emulsion (20 g) to the phosphate-functionalized polycarboxylic acid polymer solution (100 g) obtained in step S1, stir evenly to make the polymer toughening component uniformly dispersed in the polycarboxylic acid system; then add nano-hydrated calcium silicate (10.0 g), stir and react at 40℃ for 1 h, and obtain comparative example 2 after high-speed stirring and dispersion.

[0036] Comparative Example 3 This invention proposes a technical solution for preparing an interface reinforcing agent for mine support materials: a method for preparing an interface reinforcing agent for mine support materials, comprising the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Vinyl polyoxyethylene ether (50 g) was dissolved in deionized water (50 mL) and stirred until completely dissolved. Then, mercaptoacetic acid (0.15 g), ascorbic acid (0.20 g), and ferrous sulfate heptahydrate (0.01 g) were added and stirred evenly. Acrylic acid (4.0 g), phosphate methacrylate (1.0 g), and deionized water (4.0 mL) were mixed to obtain a monomer mixture. A 32% hydrogen peroxide solution (1.0 mL) was diluted and added dropwise to the reaction solution along with the monomer mixture. The dropwise addition time was controlled at 1.5 h and the reaction temperature was 30 °C. After the dropwise addition was completed, the reaction was continued at this temperature for 1.0 h. The pH of the system was adjusted to 6.0 to obtain the phosphate-functionalized polycarboxylic acid polymer. Step S2, preparation of composite reinforcement system: Add acrylic emulsion (20 g) to the phosphate-functionalized polycarboxylic acid polymer solution (100 g) obtained in step S1, stir evenly to make the polymer toughening component uniformly dispersed in the polycarboxylic acid system; then add γ-aminopropyltriethoxysilane (3.0 g), stir and react at 40°C for 1 h, and obtain Comparative Example 3 after high-speed stirring and dispersion.

[0037] Test Example 1: Adhesion Performance Test The interface reinforcing agent for the mine support material prepared in Example 1, as well as those from Comparative Examples 1-3, were added to the mine support material system. The mine support material consisted of sulfoaluminate cement, mineral powder, fine aggregate, and water. The reinforcing agent dosage was 1.0% of the mass of the cementitious material in each system, and samples were prepared according to the same water-cement ratio. After curing the samples for 28 days, a pull-out test was used to test the interfacial bond strength between the support material and the rock substrate. The test results are shown in Table 1 below. Table 1. Interfacial bond strength of reference examples, embodiments, and comparative examples. As shown in Table 1, the interfacial bonding strength of the mine support material was significantly improved after the addition of the interfacial reinforcing agent. Among them, Comparative Example 1, due to the lack of phosphate functional monomers, relied mainly on physical adsorption between the polymer and hydration products, resulting in limited reinforcing effect; Comparative Example 2, due to the lack of silane coupling, could not form a stable organic-inorganic interfacial connection; and Comparative Example 3, due to the lack of nano-reinforcing materials, had a reduced densification effect in the interfacial region.

[0038] In Example 1, a synergistic effect occurs between the phosphate-functionalized polycarboxylic acid polymer, the silane coupling agent, and the nano-reinforcing material, resulting in higher interfacial bonding performance.

[0039] Test Example 2: Compressive Strength Test Specimens were prepared according to the specifications of the mine support materials. The compressive strength was tested after 8 hours of curing under standard curing conditions (20±2 ℃, relative humidity ≥95%). The test results are shown in Table 2 below. Table 2. 8-hour compressive strength of reference examples, embodiments, and comparative examples. As shown in Table 2, compared with the blank group, the early bearing capacity and interfacial bonding performance of the mine support material interface reinforcing agent of the present invention were significantly improved after adding the interface reinforcing agent.

[0040] In the comparative examples, ordinary polycarboxylic acid, silane coupling agents, and nano-reinforcing materials improved material performance by enhancing dispersion properties, strengthening interfacial connections, and optimizing microstructure, respectively. In Example 1, phosphate-functionalized polycarboxylic acid, through carboxyl complexation, phosphate coordination, and multi-component synergistic reinforcement, achieved a compressive strength of 19.8 MPa after 8 hours, improving the rapid load-bearing capacity and interfacial stability of the mine support material.

[0041] Test Example 3: Elastic Modulus and Permeability Grade The reinforcing agents prepared in Example 1 and Comparative Examples 1-3 were added to the mine support material system, with the reinforcing agent dosage being 1.0% of the mass of the cementitious material. Specimens were prepared according to the same proportions, and after standard curing for 28 days, the static compressive modulus of elasticity and water permeability resistance of the specimens were tested.

[0042] Among them, the elastic modulus test was conducted in accordance with the "Test Method for Static Compressive Elastic Modulus of Concrete" (GB / T 50081); the impermeability test was conducted in accordance with the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082), and the impermeability grade was used to evaluate the material's resistance to water penetration.

[0043] The test results are shown in Table 3 below: Table 3. Elastic modulus and impermeability grade of reference examples, embodiments, and comparative examples. As shown in Table 3, the test results indicate that the elastic modulus and impermeability of the mine support material described in this invention are significantly improved after adding the interface reinforcing agent. This is because this invention introduces phosphate-based acrylic acid functional monomers into the polycarboxylic acid molecular chain, enabling the carboxyl and phosphate groups in the functionalized polycarboxylic acid polymer to complex with metal ions in cement hydration products, thereby increasing the bonding strength between the polymer molecules and the inorganic mineral interface. Simultaneously, the silane functional reinforcing agent hydrolyzes to form silanol groups, which then undergo a condensation reaction with hydroxyl groups on the mineral surface, constructing a stable connection between the organic and inorganic phases and reducing interface defects.

[0044] Furthermore, the nano-reinforcing material promotes the formation of hydration products through nucleation induction and optimizes the internal pore structure of the material by utilizing the nano-filling effect, reducing the proportion of harmful pores and improving the material's density. Therefore, the reinforcing agent obtained in Example 1 can simultaneously improve the structural stiffness, load-bearing stability, and impermeability of the mine support material.

[0045] Test Example 4: Adsorption Performance Test Total organic carbon (TOC) analysis was used to test the adsorption capacity of different interfacial reinforcing agents on the surface of cement particles. The test results are shown in Table 4 below: Table 4 Adsorption amounts of reference examples, embodiments, and comparative examples As shown in Table 4, in Comparative Example 1, due to the absence of the phosphate-based acrylic acid functional monomer, the polycarboxylic acid molecules mainly relied on the carboxyl groups to adsorb onto the surface of cement particles, resulting in limited adsorption capacity and a relatively small reduction in TOC. In Comparative Example 2, although the introduction of the silane coupling reinforcing agent enhanced the interfacial interaction between the organic components and inorganic minerals, the adsorption enhancement effect was limited due to the lack of ionic coordination of phosphate groups. In Comparative Example 3, the nano-reinforcing material provided additional adsorption carriers and surface active sites, further increasing the adsorption capacity of the system.

[0046] In Example 1, the carboxyl groups in the phosphate-functionalized polycarboxylic acid molecular chain can complex with Ca²⁺ on the surface of cement particles, and the phosphate groups can form stable coordination structures with Ca²⁺, Al³⁺, etc., making the polymer molecules more firmly adsorbed onto the hydration products and mineral interfaces; at the same time, the silane coupling enhancer further promotes the organic-inorganic interface connection. Therefore, Example 1 exhibits the lowest residual TOC concentration and the highest adsorption capacity.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A mine support material interface reinforcing agent, characterized in that, Includes the following components by mass percentage: The composition consists of 30-60% phosphate-functionalized polycarboxylic acid polymer, 10-30% polymer toughening component, 1-8% silane coupling reinforcing agent, 5-20% nano-reinforcing material, and deionized water. The phosphoric acid functionalized polycarboxylic acid polymer is prepared by free radical copolymerization of unsaturated polyether monomers, unsaturated carboxylic acid monomers and phosphoric acid acrylic functional monomers.

2. The interface reinforcing agent for mine support materials according to claim 1, characterized in that: The phosphate-functionalized polycarboxylic acid polymer molecular chain contains carboxyl groups, polyether side chains, and phosphate groups simultaneously; the phosphate groups are used to coordinate with metal ions in cement hydration products to enhance the bonding between polymer molecules and mineral interfaces.

3. The interface reinforcing agent for mine support materials according to claim 1, characterized in that: The unsaturated polyether monomer is one or more of methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, isobutylenyl polyoxyethylene ether, and vinyl polyoxyethylene ether; the unsaturated carboxylic acid monomer is one or more of acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid; the phosphate-based acrylic functional monomer is one or more of phosphate methacrylate, phosphate acrylate, and vinyl phosphate.

4. The interface reinforcing agent for mine support materials according to claim 1, characterized in that: The molar ratio of the unsaturated polyether monomer, the unsaturated carboxylic acid monomer, and the phosphate-based acrylic acid functional monomer is 5–20:1:0.05–0.

5.

5. The interface reinforcing agent for mine support materials according to claim 1, characterized in that: The polymer toughening component is one or more of the following: redispersible latex powder, acrylic emulsion, styrene-acrylic emulsion, styrene-butadiene emulsion, and ethylene-vinyl acetate emulsion.

6. The interface reinforcing agent for mine support materials according to claim 1, characterized in that: The silane coupling enhancer is one or more combinations of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and vinyltriethoxysilane.

7. The interface reinforcing agent for mine support materials according to claim 1, characterized in that: The nano-reinforcing material is one or more of the following: nano-silica, nano-hydrated calcium silicate, nano-alumina, nano-calcium carbonate, nano-montmorillonite, and nano-silicate.

8. A method for preparing an interface reinforcing agent for mine support materials as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step S1, Preparation of phosphate-functionalized polycarboxylic acid polymer: Unsaturated polyether monomers, chain transfer agents, reducing agents and catalysts are added to deionized water and stirred until homogeneous; then, unsaturated carboxylic acid monomers, phosphate-based acrylic functional monomers and oxidants are simultaneously added dropwise to the reaction system, and a free radical copolymerization reaction is carried out at 20~45℃; after the reaction is completed, the phosphate-functionalized polycarboxylic acid polymer is obtained after neutralization treatment. Step S2, preparation of composite reinforcement system: Add polymer toughening component, silane coupling reinforcement agent and nano-reinforcing material to the phosphate functionalized polycarboxylic acid polymer obtained in step S1, and perform mechanical stirring to make the components uniformly composite, so as to obtain the interface reinforcement agent for mine support materials.

9. The application of an interface reinforcing agent for mine support materials as described in any one of claims 1 to 7, characterized in that: The interface enhancer for mine support materials is applied to at least one of the following: mine support materials, cement-based grouting materials, shotcrete, anchoring mortar, and high-strength repair materials.

10. The application according to claim 9, characterized in that: The mine support material includes cementitious materials, which are one or more combinations of ordinary Portland cement, sulfoaluminate cement, ferroaluminate cement, mineral powder, and fly ash. The amount of interface reinforcing agent added to the mine support material is 0.5-5% of the mass of the cementitious materials.

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