Bionic composite sealing material for abandoned mine roadway gas storage and preparation method thereof

Abstract

The application discloses a kind of bionic composite sealing material for abandoned mine roadway gas storage and preparation method thereof, it is three-layer structure or two-layer structure, the three-layer structure includes bottom layer, middle layer and surface layer, the mass fraction of surface functionalization sheet layer nanofiller in each layer is as follows: bottom layer 3.5~4.0 wt%;Middle layer 6.5~7.5 wt%;Surface layer 3.5~4.0 wt%;The two-layer structure includes soft layer and hard layer, the mass fraction of surface functionalization sheet layer nanofiller in each layer is as follows: soft layer 0.5~5.5%;Hard layer 6.0~12.5%.The material of the application the gas permeation coefficient of the material is ≤5×10 ‑20 m², breaking elongation is >150%, high pressure cycle and hygrothermal aging resistance, high adhesive strength, suitable for abandoned mine roadway pressure reduction compressed air energy storage gas storage long-term sealing.

Description

Technical Field

[0001] This invention belongs to the field of high-pressure sealing materials technology for underground engineering, and particularly relates to a biomimetic composite sealing material for gas storage in abandoned mine tunnels and its preparation method. Background Technology

[0002] With the advancement of the "dual carbon" goals, compressed air energy storage (CAES), as a core technology for large-scale, long-term energy storage, urgently requires low-cost, high-safety gas storage solutions for its industrial application. Converting existing abandoned mines into CAES gas storage facilities can revitalize existing resources, reduce construction costs (saving more than 40% of investment compared to building new hard rock chambers), and simultaneously facilitate the transformation of mining areas, resulting in significant economic and social benefits.

[0003] However, sealing abandoned mine roadways faces severe technical challenges: the surrounding rock, after repeated mining, exhibits well-developed joints and fractures with poor integrity, endures long-term high-pressure cyclic inflation and deflation loads of 5-15 MPa, and faces complex environments such as water seepage, damp heat, and chemical corrosion. Existing sealing technologies have many shortcomings: (1) Steel-lined seal: It has high rigidity, poor adaptability to surrounding rock deformation, is prone to fatigue cracking under alternating stress, the weld is a potential leakage point, and the cost is high; (2) Conventional flexible materials (such as HDPE film and rubber): gas permeability coefficient is only 10 -16 ~10 -17 m², which is difficult to meet the near-zero permeability requirement, has low bonding strength with the surrounding rock (<1MPa), and is easy to peel off under high pressure; (3) Grouting and organic coating: High permeability, insufficient toughness, easy to age and fail under long-term high pressure and humid heat environment, unable to adapt to the convergence deformation of the surrounding rock; (4) Existing biomimetic materials: are mostly used in ordinary seepage prevention scenarios, are not designed for high-pressure circulation conditions in abandoned mines, lack gradient structure and interface enhancement mechanism, and have insufficient air tightness and durability.

[0004] Therefore, developing a specialized sealing material that combines near-zero permeability barrier, high deformation adaptability, strong interfacial adhesion, long service life, and easy downhole construction has become a challenge to break through the CAES technology chain in abandoned mines, and is of great significance to promoting the development of the energy storage field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a near-zero permeability biomimetic composite sealing material and its preparation method for use in the conversion of abandoned mine roadways into compressed air energy storage and gas storage facilities.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A biomimetic composite sealing material for gas storage in abandoned mine tunnels has a three-layer or two-layer structure, each layer containing: fluorine-containing segment modified polyether polyurethane, polyetheramine modified bisphenol A epoxy resin, surface-functionalized sheet nanofiller, active additives, anti-aging agent and curing agent. The three-layer structure includes a bottom layer, a middle layer, and a top layer, and the mass fraction of surface-functionalized sheet-like nanofillers in each layer is: The bottom layer is 3.5~4.0 wt%; Middle layer 6.5~7.5 wt% Surface layer 3.5~4.0 wt% The two-layer structure includes a soft layer and a hard layer, and the mass fraction of surface-functionalized sheet-like nanofillers in each layer is: Soft layer 0.5~5.5%; Hard layer 6.0~12.5%; The fluorinated segment is a polyurethane side chain grafted with perfluorooctyl ethyl acrylate. The surface-functionalized sheet nanofiller is a sheet nanofiller treated with a modifier; the sheet nanofiller is one or more composites of montmorillonite, hydrotalcite, or graphene; the modifier is γ-(methacryloyloxy)propyltrimethoxysilane or 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid.

[0007] Furthermore, by mass percentage, the total mass percentage of each component in the biomimetic composite sealing material is as follows: 30-50 parts of fluorinated segment modified polyether polyurethane, 20-40 parts of polyetheramine modified bisphenol A epoxy resin, 3-8 parts of surface functionalized sheet nanofiller, 2-5 parts of active additives, 0.5-2 parts of anti-aging agent, and 3-6 parts of curing agent.

[0008] Furthermore, the fluorinated segment modified polyether polyurethane has a soft segment to hard segment mass ratio of 1.2 to 1.8:1, and the fluorinated segment molar content accounts for 5% to 10% of the polyurethane molecular chain.

[0009] Furthermore, the preparation method of the fluorinated segment modified polyether polyurethane is as follows: polypropylene glycol and 4,4'-diphenylmethane diisocyanate are reacted at 75~85℃, and then 1,4-butanediol is added for chain extension reaction to obtain polyurethane prepolymer; perfluorooctyl ethyl acrylate and azobisisobutyronitrile are mixed and added dropwise to polyurethane prepolymer, and grafting reaction is carried out at 65~75℃.

[0010] Furthermore, in the polyetheramine-modified bisphenol A type epoxy resin, the mass ratio of polyetheramine to epoxy resin is 0.1~0.3:1.

[0011] Furthermore, the preparation method of the polyetheramine-modified bisphenol A epoxy resin is as follows: heating the bisphenol A epoxy resin to 55~65℃, adding polyetheramine, and stirring the reaction at 75~85℃.

[0012] Furthermore, the preparation method of the surface-functionalized sheet nanofiller is as follows: the sheet nanofiller is added to anhydrous ethanol and ultrasonically dispersed to form a suspension with a mass concentration of 5% to 10%; a modifier is added at 5% to 10% of the mass of the sheet nanofiller, and the mixture is stirred and reacted at 60 to 80°C.

[0013] Furthermore, the active agent is a bifunctional active agent, which is γ-glycidoxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane. The anti-aging agent is a compound anti-aging agent, which is a compound system of hindered phenolic antioxidants and benzotriazole ultraviolet absorbers, with a mass ratio of 1:1 to 2. The curing agent is a composite curing agent, which is a compound system of isophorone diamine and polyamide resin, with a mass ratio of 2~3:1.

[0014] The present invention also provides a method for preparing the biomimetic composite sealing material for gas storage in abandoned mine tunnels, comprising the following steps: (1) Fluorine-containing segment modified polyether polyurethane and polyetheramine modified bisphenol A epoxy resin are stirred and dispersed evenly at 60~80℃ to obtain a composite matrix; (2) Add surface-functionalized sheet nanofillers and active additives to the composite matrix and disperse them evenly to obtain a filler suspension; prepare corresponding filler suspensions according to the mass fraction of surface-functionalized sheet nanofillers in each layer of the sealing material. (3) Reduce the temperature of the filler suspension to 40~50℃, add anti-aging agent and curing agent, stir and mix evenly to obtain the precursors corresponding to the filler content and each layer of the sealing material; (4) The biomimetic composite sealing material is formed by solution casting-gradient molding process or reactive extrusion-laminar composite process, and then cured and maintained. The solution casting-gradient molding process is as follows: precursors with filler contents of 3.5~4.0%, 6.5~7.5%, and 3.5~4.0% are cast sequentially from bottom to top into the mold, the solvent is evaporated at 30~50℃, and then solidified to form a three-layer structure; The reactive extrusion-laminar composite process is as follows: the precursor is used to prepare hard layer masterbatch and soft layer masterbatch through a twin-screw extruder, the filler content of the hard layer masterbatch is 6.0~12.5wt%, and the filler content of the soft layer masterbatch is 0.5~5.5wt%; then the hard layer masterbatch and soft layer masterbatch are hot-pressed to form a two-layer structure.

[0015] Furthermore, in the three-layer structure, the bottom layer has a thickness of 0.5~1mm, the middle layer has a thickness of 1~2mm, and the surface layer has a thickness of 0.5~1mm; in the two-layer structure, the soft layer has a thickness of 1~1.5mm, and the hard layer has a thickness of 0.5~1mm.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: Addressing the core need for sealing gas storage in abandoned mine roadways, and resolving technical issues such as the contradiction between high barrier properties and high toughness, insufficient adhesion and resistance to complex environments, and poor adaptability to high-pressure cyclic conditions in existing sealing materials, this invention provides a biomimetic composite sealing material with near-zero permeability, high deformation adaptability, long lifespan, and easy construction. It also provides a standardized preparation method to achieve long-term reliable sealing under high-pressure cyclic conditions in abandoned mine gas storage facilities.

[0017] The core innovation of this invention lies in drawing upon the synergistic reinforcement mechanism of the "brick-and-mortar" structure of nacreous shells, combined with the design concept of "rigid-flexible gradient composite," to construct a low-medium-low three-layer gradient functional structure (solution casting process) with a strong adhesive bottom layer, a stress buffer middle layer, and a high barrier surface layer, or a double-layer structure (reactive extrusion process) with a strong adhesive soft layer and a high barrier hard layer. The comprehensive sealing performance of the three-layer structure is superior to that of the double-layer structure, which is suitable for scenarios with limited construction space in mine tunnels. In the three-layer structure, the low filler content in the surface layer forms a dense gas barrier layer, achieving near-zero permeability sealing; the moderate filler content in the middle layer balances toughness and strength, dissipating stress caused by high-pressure cyclic loads; and the low filler content in the bottom layer improves the adhesion performance between the material and the concrete / rock substrate, preventing the material from peeling off from the surrounding rock. Simultaneously, through modification of the polymer matrix, surface functionalization of the nanofillers, and synergistic compounding of various components, the technical contradiction between high barrier and high toughness is resolved, improving the material's comprehensive performance in terms of high-pressure cycling resistance and resistance to damp heat aging.

[0018] The material of this invention has a gas permeability coefficient (helium, 25°C) ≤ 5 × 10⁻⁶. -20 With a diameter of m², elongation at break >150%, resistance to high-pressure cycling and damp heat aging, high bonding strength, and adaptability to the deformation characteristics of surrounding rock in abandoned mines, this material is suitable for long-term sealing of abandoned mine roadways converted into compressed air energy storage facilities. It can also be extended to high-standard seepage prevention in major underground projects such as underground hydrogen storage facilities, natural gas storage facilities, deep tunnels, and nuclear waste geological disposal sites. This solution addresses the contradiction between high barrier properties and high toughness, as well as insufficient resistance to various working conditions, of existing sealing materials. It also boasts advantages such as low cost and ease of construction, resulting in significant economic and social benefits. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of the material synthesis process; Figure 2 Schematic diagrams of the material structure: (a) is a schematic diagram of a three-layer gradient structure, and (b) is a schematic diagram of a two-layer structure. Detailed Implementation

[0021] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0022] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0023] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0024] In some embodiments, the biomimetic composite sealing material for gas storage in abandoned mine tunnels of the present invention has a three-layer or two-layer structure; each layer contains: fluorinated segment modified polyether polyurethane, polyetheramine modified bisphenol A epoxy resin, surface functionalized sheet nanofiller, active additives (e.g., bifunctional active agents), anti-aging agents (e.g., compounded anti-aging agents), and curing agents (e.g., composite curing agents).

[0025] The three-layer structure includes a bottom layer, a middle layer, and a top layer. The mass fraction of surface-functionalized sheet-like nanofillers in each layer is as follows: Bottom layer: 3.5~4.0 wt% Middle layer: 6.5~7.5 wt% Surface layer: 3.5~4.0 wt%.

[0026] The middle layer is the core layer with high filler content, playing a key role in stress buffering. The surface and bottom layers, with low filler content, respectively ensure high airtightness and strong adhesion.

[0027] The two-layer structure includes a soft layer and a hard layer (the hard layer serves as the surface layer). The mass fraction of surface-functionalized sheet-like nanofillers in each layer is: Soft layer: 0.5~5.5%; Hard layer: 6.0~12.5%.

[0028] The total mass parts of each component in the biomimetic composite sealing material are as follows: 30-50 parts of fluorinated segment modified polyether polyurethane, 20-40 parts of polyetheramine modified bisphenol A epoxy resin, 3-8 parts of surface functionalized sheet nanofiller, 2-5 parts of bifunctional active additive, 0.5-2 parts of compounded anti-aging agent, and 3-6 parts of composite curing agent.

[0029] In some embodiments, apart from the surface-functionalized sheet nanofiller, the other components have the same mass fraction in each layer.

[0030] In some embodiments, the fluorinated segment modified polyether polyurethane (TPU) has a soft segment to hard segment mass ratio of 1.2 to 1.8:1; the hard segment is 4,4'-diphenylmethane diisocyanate (MDI, molecular formula C64-C ... 15 H 10 The polycondensation segment of N2O2 and 1,4-butanediol (BDO) provides the material with strength and hardness; the soft segment is polypropylene glycol (PPG-2000, molecular formula (C3H6O)). n The fluorinated segments (OH) provide the material with toughness and deformability. These fluorinated segments are polyurethane side chains grafted with perfluorooctyl ethyl acrylate (PFOEA), and their molar content accounts for 5%–10% of the polyurethane molecular chain, improving the material's airtightness and chemical resistance.

[0031] The preparation method of the fluorinated segment modified polyether polyurethane is as follows: Polypropylene glycol (PPG-2000) is vacuum dehydrated at 100~110℃ for 2~4h, and then reacted with 4,4'-diphenylmethane diisocyanate (MDI) at 75~85℃ (preferably 80℃) for 1.5~2.5h (preferably 2h). 1,4-Butanediol (BDO) is added for chain extension reaction for 0.5~1.5h (preferably 1h) to obtain a polyurethane prepolymer. Perfluorooctyl ethyl acrylate (PFOEA) and azobisisobutyronitrile (AIBN) are mixed and added dropwise to the polyurethane prepolymer at a dropping rate of 1~2 drops / second. Grafting reaction is carried out at 65~75℃ (preferably 70℃) for 2.5~3.5h (preferably 3h). The mixture is cooled to room temperature to obtain the final product. The mass ratio of soft to hard segments is controlled at 1.2~1.8:1, and the molar content of fluorinated segments is 5%~10%.

[0032] In some embodiments, the polyetheramine-modified bisphenol A epoxy resin has a molecular weight of 200-400; the epoxy resin is bisphenol A type E-51 epoxy resin with a solid content of over 99%; the mass ratio of polyetheramine to epoxy resin is 0.1-0.3:1; and the modified epoxy resin has a solid content of 85-90%, which enhances the strength and interfacial adhesion of the material.

[0033] The preparation method of the polyetheramine-modified bisphenol A type epoxy resin is as follows: heating the bisphenol A type E-51 epoxy resin to 55~65℃ (preferably 60℃), adding polyetheramine (molecular weight 200~400) at a mass ratio of 0.1~0.3:1, stirring and reacting at 75~85℃ (preferably 80℃) for 1.5~2.5h (preferably 2h), and cooling to room temperature to obtain the modified epoxy resin with a solid content of 85~90%.

[0034] In some embodiments, the surface-functionalized sheet-like nanofiller is one or more composites of montmorillonite, hydrotalcite, or graphene treated with a modifier. The modifier is γ-(methacryloyloxy)propyltrimethoxysilane (KH-570) or 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid. After modification, the filler interlayer spacing is ≥20 nm, and the surface is grafted with amino or epoxy active groups to improve the compatibility between the filler and the polymer matrix.

[0035] The preparation method of the surface-functionalized sheet nanofiller is as follows: (1) Preparation of suspension: Add the sheet-like nanofiller (one or more of montmorillonite, hydrotalcite or graphene) to anhydrous ethanol and ultrasonically disperse it for 30 to 60 minutes at a power of 200 to 300W to form a suspension with a mass concentration of 5% to 10%. (2) Modification reaction: Add modifier at 5%~10% of the mass of the sheet nanofiller, and stir the reaction at 60~80℃ and 300~500r / min for 2~4h to allow the modifier to be fully grafted onto the surface of the filler. (3) Washing and removing impurities: Filter and collect the solid product, wash it with anhydrous ethanol 3 to 5 times to remove unreacted modifiers; (4) Vacuum drying: The washed solid product is vacuum dried at 45~50℃ for 8~12h to obtain surface functionalized sheet nanofiller.

[0036] In some embodiments, the bifunctional active agent is γ-glycidoxypropyltrimethoxysilane (KH-560) or γ-aminopropyltriethoxysilane (KH-550), which plays an interfacial coupling role and enhances the binding force between the components.

[0037] In some embodiments, the compound anti-aging agent is a compound system of hindered phenolic antioxidant and benzotriazole ultraviolet absorber, with a mass ratio of 1:1 to 2, which improves the material's resistance to damp heat and aging; the hindered phenolic antioxidant is antioxidant 1010 or antioxidant 1076, and the benzotriazole ultraviolet absorber is UV-531 or UV-327.

[0038] In some embodiments, the composite curing agent is a compound system of isophorone diamine and polyamide resin, with a mass ratio of 2 to 3:1, to achieve efficient curing of the material while taking into account both curing speed and post-curing performance.

[0039] In some embodiments, the preparation method of the biomimetic composite sealing material for gas storage in abandoned mine tunnels according to the present invention includes the following steps: (1) Matrix premixing: Fluorine-containing segment modified polyether polyurethane and polyetheramine modified bisphenol A epoxy resin are added to the reactor in proportion and stirred for 30-40 minutes at 60-80℃ and 500-800 r / min to obtain a uniformly dispersed composite matrix without lumps.

[0040] (2) Filler dispersion: The surface-functionalized sheet nanofiller is divided into three or two parts according to the design ratio. One part is added to the composite matrix along with the bifunctional active agent. First, it is sheared at a speed of 3000~5000 r / min for 20~30 min, and then ultrasonically dispersed at a power of 300~500 W for 40~60 min to form a stable suspension without agglomeration, ensuring that the filler is uniformly dispersed in the matrix. Precursors with different filler contents are prepared according to the above method.

[0041] (3) Additive compounding: The temperature of the reactor is reduced to 40~50℃, and the compound anti-aging agent and compound curing agent are added. The mixture is stirred for 15~20min at a speed of 300~500r / min. After uniform mixing, the precursor of the sealing material is obtained. Low-temperature stirring avoids premature reaction of the curing agent. The preparation is repeated to obtain precursors with different filler contents.

[0042] (4) Molding and curing: The solution casting-gradient molding process or reactive extrusion-laminar composite process is used for molding, and then the initial product is obtained by curing.

[0043] The solution casting-gradient molding process requires the preparation of precursors according to different filler contents. The total amount of surface functionalized sheet nanofillers added is 3 to 8 parts, and the filler content of each layer is allocated according to the design ratio.

[0044] In some embodiments, the solution casting-gradient molding process is as follows: sealing material precursors with filler contents of 3.5~4.0%, 6.5~7.5%, and 3.5~4.0% are sequentially cast into a mold from bottom to top, with the bottom layer having a casting thickness of 0.5~1mm, the middle layer 1~2mm, and the top layer 0.5~1mm. The solvent evaporation temperature is controlled at 30~50℃ and the evaporation time is controlled at 2~4h. The solvent evaporation induces the nanosheets to oriented and align, forming a low-medium-low three-layer gradient functional structure. Then, it is cured at room temperature to 60℃ for 4~8h. This process provides a low-medium-low three-layer gradient structure with optimal overall sealing performance. The high filler content in the middle layer forms a stress buffer core, while the low filler content in the top and bottom layers ensures high airtightness and strong adhesion, respectively.

[0045] In some embodiments, the reactive extrusion-laminar composite process is as follows: a high-filler-content hard layer masterbatch and a low-filler-content soft layer masterbatch are prepared using a twin-screw extruder. The barrel temperature of the twin-screw extruder is 80~120℃, the screw speed is 100~200r / min, the filler content of the hard layer masterbatch is 6.0~12.5wt%, and the filler content of the soft layer masterbatch is 0.5~5.5wt%. The hard layer masterbatch and the soft layer masterbatch are then composited using a hot press laminator. The thickness of the soft layer is 1~1.5mm, and the thickness of the hard layer is 0.5~1mm. The hot pressing conditions are 80~100℃, 5~10MPa, and 1~2h, followed by natural cooling to room temperature. This process is a two-layer structure and is suitable for mine roadway scenarios where construction space is narrow and casting processes are difficult to implement. Its sealing performance is slightly lower than that of a three-layer gradient structure.

[0046] (5) Post-treatment: Trim the edges of the cured initial product to remove waste material, and then cure it at room temperature and humidity of 30%~70% for 24~48 hours to obtain biomimetic composite sealing material.

[0047] In some embodiments, the comprehensive performance indicators of the sealing material meet the following requirements: gas permeability coefficient (helium, 25°C) ≤ 5 × 10⁻⁶. -20 m 2 / s, elongation at break >150%, tensile strength ≥8MPa, Shore hardness (A) 85~95, bond strength with concrete / rock substrate >2MPa, performance degradation <15% after 1000 cycles of 0~10MPa pressure, and performance degradation <15% after aging for 1000 hours at 40℃ and 90% relative humidity.

[0048] With the same total filler content, the three-layer gradient structure exhibits superior overall performance compared to the two-layer structure: its gas permeability coefficient is 20%–30% lower, its high-pressure cycle resistance degradation is 3–5 percentage points lower, and its overall performance is improved by 10%–15%. When the total filler content of the two-layer structure is increased to 6–8 parts, its gas barrier performance can approach or even slightly surpass that of the medium-filler three-layer structure, but its elongation at break and deformation adaptability will decrease accordingly. The single-layer homogeneous structure has the worst performance; materials without matrix modification or filler surface functionalization show a degradation of over 30% in both aging resistance and cycle resistance.

[0049] Example 1 (Solution casting-gradient molding three-layer structure) 1. Raw material ratio (by mass parts) 40 parts of fluorinated segment modified polyether polyurethane (soft segment to hard segment mass ratio 1.5:1, fluorinated segment molar content 7%), 30 parts of polyetheramine modified bisphenol A epoxy resin (polyetheramine molecular weight 300, polyetheramine to EP mass ratio 0.2:1), 4 parts of surface-functionalized montmorillonite, 3 parts of KH-560, 1 part of compounded anti-aging agent (antioxidant 1010:UV-531=1:1.5), and 4 parts of composite curing agent (isophorone diamine: polyamide resin=2.5:1).

[0050] 2. Preparation of fluorinated segment modified polyether polyurethane: 100g of polypropylene glycol (PPG-2000) was vacuum dehydrated at 100℃ for 2h, reacted with 114g of 4,4'-diphenylmethane diisocyanate (MDI) at 80℃ for 2h, and then 36g of 1,4-butanediol (BDO) was added for chain extension reaction for 1h to obtain a polyurethane prepolymer; 16.5g of perfluorooctyl ethyl acrylate (PFOEA) and 0.13g of azobisisobutyronitrile (AIBN) were mixed and added dropwise to the polyurethane prepolymer at 1 drop / second, and grafted at 70℃ for 3h. After cooling to room temperature, the polyurethane prepolymer was obtained with a soft segment mass ratio of 1.5:1 and a fluorinated segment molar content of 7%.

[0051] 3. Preparation of polyetheramine-modified bisphenol A type epoxy resin: 25g of bisphenol A type E-51 epoxy resin was added to a reaction vessel, heated to 60℃ and stirred. 5g of polyetheramine (molecular weight 300) was slowly added at a mass ratio of 0.2:1 (controlled at 15~20 minutes to prevent local burst polymerization). The mixture was heated to 80℃ and stirred for 2 hours. After cooling to room temperature, the modified solid content was 88%.

[0052] 4. Preparation of surface-functionalized montmorillonite: (1) Add 4.5g of montmorillonite to 51.8g of anhydrous ethanol and ultrasonically disperse at 250W for 45min to form a suspension with a mass concentration of 8%; (2) Add 0.32g KH-570 at 7% of the mass of montmorillonite, and stir at 70℃ and 400r / min for 3h. (3) Filter and collect the solid, wash it 4 times with 25 mL of anhydrous ethanol to remove unreacted KH-570; (4) Vacuum drying at 48℃ for 10h, passing through a 200-mesh sieve, and grafting epoxy groups on the surface to obtain approximately 3.96g of surface-functionalized montmorillonite with an interlayer spacing of 22nm.

[0053] 5. Preparation of the main sealing material: (1) Matrix premixing: 40 parts of modified TPU and 30 parts of modified EP were added to the reactor and stirred at 70℃ and 650r / min for 35min to obtain the composite matrix, which was then divided into three equal parts; (2) Filler dispersion: Take 1 part of surface-functionalized montmorillonite and 1 part of KH-560 and add them to the composite matrix obtained in step (1). Shear at 4000 r / min for 25 min and ultrasonically disperse at 400 W for 50 min to obtain filler suspension a; Take another 2 parts of montmorillonite and 1 part of KH-560 to prepare filler suspension b according to the above method; Finally, take 1 part of montmorillonite and 1 part of KH-560 to prepare filler suspension c according to the above method. The three suspensions are prepared independently. (3) Additive compounding: The reactor was cooled to 45°C, and 1 / 3 (0.33 parts) of compound anti-aging agent and 1 / 3 (1.33 parts) of compound curing agent were added to each part of filler suspension. The mixture was stirred at 400 r / min for 18 min to obtain precursor a (filler content 3.7%), precursor b (filler content 7.1%), and precursor c (filler content 3.7%). (4) Molding and curing: The solution casting-gradient molding process is adopted. Precursor a, precursor b and precursor c are sequentially cast to the mold with casting thicknesses of 0.5 mm, 1.5 mm and 0.5 mm respectively. The solvent is evaporated at 40℃ for 3 hours and cured at 40℃ for 6 hours to obtain the initial product. (5) Post-treatment: After trimming, cure at room temperature and 50% humidity for 36 hours to obtain the finished product.

[0054] 6. Performance Testing In accordance with relevant national standards and industry specifications, the performance of the prepared sealing material was tested, including gas permeability coefficient, elongation at break, tensile strength, Shore hardness, bond strength to concrete substrate, performance degradation after 1000 pressure cycles (0~10MPa), performance degradation after 1000h damp heat aging (40℃ / 90%RH), viscosity (25℃), and surface tension.

[0055] Gas permeability coefficient (helium, 25 ℃): The pressure difference method was used, according to GB / T 1038.1-2022. The test medium was helium with a purity of 99.999%, the test pressure was 0.1MPa, and the sample thickness was 2.5mm (three-layer structure) / 2.0mm (two-layer structure).

[0056] Elongation at break and tensile strength: According to GB / T 1040.3-2006, dumbbell-shaped specimens (Type I) were used, the tensile rate was 50 mm / min, and the test temperature was 25℃.

[0057] Shore hardness (A): According to GB / T 2411-2008, a Shore A hardness tester is used. The reading is taken 15 seconds after the indenter contacts the sample, and the average value of 5 measuring points is taken.

[0058] Bond strength with concrete / rock substrate: According to GB / T 16777-2008, the figure-eight mold method was used. The concrete substrate strength grade was C30, and the rock substrate was sandstone. The curing conditions were 25℃ and 50% relative humidity. The test was conducted after 7 days of curing.

[0059] Performance degradation after 1000 pressure cycles (0~10 MPa): There is no specific national standard, but the industry-standard high-pressure cycling test method is adopted: The sample is sealed in a high-pressure gas cycling test device, the pressure is increased to 10 MPa at a rate of 0.5 MPa / s, held for 30 s, and then depressurized to 0 MPa at a rate of 0.5 MPa / s, held for 30 s, and this completes one cycle; after 1000 consecutive cycles, the tensile strength and gas permeability coefficient of the sample are tested, and the performance degradation rate is calculated according to the formula: Performance degradation rate = (initial performance - post-cycle performance) / initial performance × 100%.

[0060] Performance degradation after 1000 h of damp heat aging (40 ℃ / 90% RH): According to GB / T 1740-2007 "Test Method for Damp Heat Resistance of Coating Film", the sample was placed in a constant temperature and humidity test chamber at 40 ℃ and 90% relative humidity for 1000 h of continuous aging. After that, the sample was taken out and placed at 25 ℃ for 24 h. The tensile strength and gas permeability coefficient were tested. The performance degradation rate was calculated according to the above formula.

[0061] Viscosity (25℃): According to GB / T 2794-2013, an NDJ-1 type rotational viscometer was used, with a test temperature of 25℃ and a rotation speed of 12 r / min.

[0062] Surface tension: According to GB / T 22237-2008, a contact angle measuring instrument was used, and the test liquids were deionized water and diiodomethane. The surface tension of the material was calculated by the Owens-Wendt method.

[0063] The sealing material prepared in this embodiment was subjected to performance testing, and the results were as follows: gas permeability coefficient (helium, 25℃) 3.2 × 10⁻⁶ -20 m 2 / s, elongation at break 165%, tensile strength 8.5MPa, Shore hardness (A) 88, bond strength to concrete substrate 2.3MPa, performance degradation 12% after 1000 cycles of 0~10MPa pressure, performance degradation 11% after 1000h aging at 40℃ / 90%RH, viscosity (25℃): 65mPa·s, surface tension: 32mN / m, meeting the preset performance indicators. It exhibits optimal comprehensive performance of the filler, balancing barrier, toughness, and cycle resistance, making it suitable for main gas storage tunnels with large surrounding rock deformation.

[0064] Example 2 (Reactive extrusion-laminated composite bilayer structure) 1. Raw material ratio (by mass parts) 30 parts of fluorinated segment modified polyether polyurethane (soft segment to hard segment mass ratio 1.2:1, fluorinated segment molar content 5%), 40 parts of polyetheramine modified bisphenol A epoxy resin (polyetheramine molecular weight 200, polyetheramine to EP mass ratio 0.1:1), 3 parts of surface-functionalized graphene / hydrotalcite composite filler, 2 parts of KH-550, 0.5 parts of compounded anti-aging agent (antioxidant 1076:UV-327=1:1), and 3 parts of composite curing agent (isophorone diamine: polyamide resin=2:1).

[0065] 2. Preparation of fluorinated segment modified polyether polyurethane / polyetheramine modified bisphenol A epoxy resin: The preparation method of Example 1 was followed, with the mass ratio of soft to hard segments controlled at 1.2:1, the molar content of fluorinated segments at 10%, the mass ratio of polyetheramine to EP at 0.3:1, and the solid content after modification at 90%.

[0066] 3. Preparation of surface-functionalized graphene / hydrotalcite composite fillers: (1) After combining graphene (1.7g) and hydrotalcite (1.7g) in a 1:1 ratio, add 64.6g of anhydrous ethanol and ultrasonically disperse at 200W for 30min to form a suspension with a mass concentration of 5%. (2) Add 0.17g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid at 5% of the filler mass, and stir at 60℃ and 300r / min for 2h. (3) Filter and collect the solid, and wash it three times with 25 mL of anhydrous ethanol; (4) Vacuum drying at 45℃ for 8 hours yielded approximately 3g of surface-functionalized composite filler with amino grafts on the surface and an interlayer spacing of 20nm.

[0067] 4. Preparation of the main sealing material (1) Matrix premixing: 30 parts of modified TPU and 40 parts of modified EP were added to the reactor and stirred at 60℃ and 500r / min for 30min to obtain the composite matrix, which was then divided into two equal parts. (2) Packer dispersion: Take 0.3 parts of composite packer and 1 part of KH-550 and add them to 1 part of composite matrix. Shear at 3000 r / min for 20 min and ultrasonically disperse at 300 W for 40 min to obtain stable suspension a; Take another 2.7 parts of composite packer and 1 part of KH-550 and add them to 1 part of composite matrix to prepare suspension b according to the above method; The two suspensions are prepared independently. (3) Additive compounding: Cool the reactor to 40°C, add 0.25 parts of compound anti-aging agent and 1.5 parts of compound curing agent to suspension a, stir at 300 r / min for 15 min to obtain precursor a (filler content 0.8%, soft layer); add 0.25 parts of compound anti-aging agent and 1.5 parts of compound curing agent to suspension b, stir at 300 r / min for 15 min to obtain precursor b (filler content 6.7%, hard layer); (4) Molding and curing: The reactive extrusion-laminar composite process is adopted. The precursor a and precursor b are prepared into soft layer masterbatch and hard layer masterbatch respectively at 80℃ and 100r / min using a twin-screw extruder. The soft layer is 1.2mm thick and the hard layer is 0.8mm thick. The composite is formed by hot pressing at 80℃, 5MPa and 1h, and then naturally cooled to room temperature. (5) Post-treatment: After trimming, cure for 24 hours at room temperature and 30% humidity to obtain the finished product.

[0068] 5. Performance Testing The test results are as follows: Gas permeability coefficient (helium, 25℃) 4.1×10 -20 m 2 / s, elongation at break 172%, tensile strength 8.0MPa, Shore hardness (A) 85, bond strength to rock matrix 2.1MPa, performance degradation of 13% after 1000 cycles of 0~10MPa pressure, and performance degradation of 12% after aging at 40℃ / 90%RH for 1000h, meeting the preset performance indicators.

[0069] Example 3 (Reactive extrusion-laminated composite bilayer structure) 1. Raw material ratio (by mass parts) 50 parts of fluorinated segment modified polyether polyurethane (soft segment to hard segment mass ratio 1.8:1, fluorinated segment molar content 10%), 20 parts of polyetheramine modified bisphenol A epoxy resin (polyetheramine molecular weight 400, polyetheramine to EP mass ratio 0.3:1), 8 parts of surface-functionalized montmorillonite / hydrotalcite composite filler, 5 parts of KH-560, 2 parts of compounded anti-aging agent (antioxidant 1010: UV-531 = 1:2), and 6 parts of composite curing agent (isophorone diamine: polyamide resin = 3:1).

[0070] 2. Preparation of fluorinated segment modified polyether polyurethane / polyetheramine modified bisphenol A epoxy resin: The preparation method of Example 1 was followed, with the mass ratio of soft to hard segments controlled at 1.8:1, the molar content of fluorinated segments at 10%, the mass ratio of polyetheramine to EP at 0.3:1, and the solid content after modification at 90%.

[0071] 3. Preparation of surface-functionalized montmorillonite / hydrotalcite composite fillers (1) Add anhydrous ethanol to the montmorillonite / hydrotalcite compound at a ratio of 2:1 and ultrasonically disperse at 300W for 60 minutes to form a suspension with a mass concentration of 10%. (2) Add KH-570 at 10% of the filler mass and stir at 80℃ and 500r / min for 4h; (3) Filter and collect the solid, and wash it 5 times with anhydrous ethanol; (4) Vacuum drying at 50℃ for 12h yields surface-functionalized composite filler with interlayer spacing of 25nm and surface grafted with epoxy groups.

[0072] 3. Preparation of the main sealing material (1) Matrix premixing: 50 parts of modified TPU and 20 parts of modified EP were added to the reactor and stirred at 80℃ and 800r / min for 40min to obtain the composite matrix, which was then divided into two equal parts. (2) Packing material dispersion: Take 2.3 parts of composite packing material and 2.5 parts of KH-560, perform high-speed shearing at 5000 r / min for 30 min, and ultrasonic dispersion at 500 W for 60 min to obtain stable suspension a; take 5.7 parts of composite packing material and 2.5 parts of KH-560, perform high-speed shearing at 5000 r / min for 30 min, and ultrasonic dispersion at 500 W for 60 min to obtain stable suspension b; (3) Additive compounding: Cool the reactor to 50°C, add 1 part of compound anti-aging agent and 3 parts of compound curing agent to suspension a, stir at 500 r / min for 20 min to obtain precursor a (filler content 5.3%); add 1 part of compound anti-aging agent and 3 parts of compound curing agent to suspension b, stir at 500 r / min for 20 min to obtain precursor b (filler content 12.1%).

[0073] (4) Molding and curing: The reactive extrusion-laminar composite process is adopted. The precursor a and precursor b are prepared into soft layer masterbatch and hard layer masterbatch respectively at 120℃ and 200r / min using a twin-screw extruder. The soft layer thickness is 1.5mm and the hard layer thickness is 0.5mm. The composite molding is carried out by hot press laminating at 100℃, 10MPa and 2h, and then naturally cooled to room temperature. (5) Post-treatment: After trimming, cure at room temperature and 70% humidity for 48 hours to obtain the finished product.

[0074] 5. Performance Testing The test results are as follows: Gas permeability coefficient (helium, 25℃) 2.8×10 -20 m 2 / s, elongation at break 155%, tensile strength 9.2MPa, Shore hardness (A) 95, bond strength to concrete substrate 2.5MPa, performance degradation of 10% after 1000 cycles of 0~10MPa pressure, and performance degradation of 9% after aging at 40℃ / 90%RH for 1000h, which is better than the preset performance indicators.

[0075] Comparative Example 1 (Single-layer structure) The raw material ratio and preparation method are the same as in Example 1, except that the molding and curing process is changed to single-layer casting (filler content 3.7%, thickness 2.5mm), and the other conditions remain unchanged.

[0076] Performance test results: Gas permeability coefficient 1.5×10 -19 m 2 / s, elongation at break 140%, tensile strength 7.2MPa, performance degradation 20% after pressure cycling, performance degradation 22% after damp heat aging, performance is far lower than three-layer structure, airtightness and cycle resistance are significantly reduced.

[0077] Comparative Example 2 (filler content exceeds the range) The raw material ratio and preparation method are the same as in Example 1, except that the filler content of each layer is changed to 5% for the bottom layer, 7% for the middle layer, and 5% for the top layer (the bottom and top layers exceed 3.5-4.0%, and the middle layer is within the reasonable range of 6.5-7.5%), and the other conditions remain unchanged.

[0078] Performance test results: Gas permeability coefficient 3.0 × 10⁻⁶ -20 m 2 / s, but the elongation at break is only 120%, and the bond strength with the concrete substrate is 1.5MPa. The excessive filler content leads to a significant decrease in toughness and adhesion, making it unable to adapt to the deformation of the surrounding rock.

[0079] Comparative Example 3 (TPU without fluorinated segments) The raw material ratio and preparation method are the same as in Example 1, except that the fluorinated segment modified TPU is replaced with ordinary polyether polyurethane (no fluorinated segment, soft segment ratio 1.5:1), and the other conditions remain unchanged.

[0080] Performance test results: Gas permeability coefficient 8.6 × 10⁻⁶ -19 m 2 After damp heat aging, the performance degrades by 28%, and the absence of fluorine-containing segments leads to a significant decrease in airtightness and chemical resistance.

[0081] Comparative Example 4 (EP without polyetheramine modification) The raw material ratio and preparation method are the same as in Example 1, except that the polyetheramine modified EP is replaced with ordinary bisphenol A type E-51 epoxy resin, and the other conditions remain unchanged.

[0082] Performance test results: The bond strength with the concrete substrate is 1.2 MPa, and the elongation at break is 110%. The unmodified epoxy resin results in insufficient adhesion and toughness, making it easy to peel off from the surrounding rock.

[0083] Comparative Example 5 (Laminated nanofiller without surface functionalization) The raw material ratio and preparation method are the same as in Example 1, except that the surface-functionalized montmorillonite is replaced with unmodified montmorillonite, and all other conditions remain unchanged.

[0084] Performance test results: Gas permeability coefficient 7.9 × 10⁻⁶ -19 m 2 The tensile strength is 6.5 MPa. The agglomeration of the filler leads to poor dispersibility, resulting in a decrease in air tightness and strength.

[0085] Comparative Example 6 (without bifunctional active additives) The raw material ratio and preparation method are the same as in Example 1, except that the bifunctional active agent KH-560 is removed, and the other conditions remain unchanged.

[0086] Performance test results: interlayer bonding strength decreased, interlayer cracking occurred after 500 pressure cycles, performance degradation was 35%, the lack of coupling agent resulted in insufficient bonding force between each layer and the components, making it easy to delaminate.

[0087] Comparative Example 7 (without compound anti-aging agents) The raw material ratio and preparation method are the same as in Example 1, except that the compound anti-aging agent is removed and the other conditions remain unchanged.

[0088] Performance test results: After 1000 hours of damp heat aging, the performance decreased by 40%, and the tensile strength dropped to 4.2 MPa. The lack of anti-aging agent caused the material to age rapidly in a damp heat environment, resulting in a significant reduction in service life.

[0089] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A biomimetic composite sealing material for gas storage in abandoned mine tunnels, characterized in that, It has a three-layer or two-layer structure, each layer containing: fluorinated segment modified polyether polyurethane, polyetheramine modified bisphenol A epoxy resin, surface functionalized sheet nanofiller, active additives, anti-aging agent and curing agent. The three-layer structure includes a bottom layer, a middle layer, and a top layer, and the mass fraction of surface-functionalized sheet-like nanofillers in each layer is: The bottom layer is 3.5~4.0 wt%; Middle layer 6.5~7.5 wt% Surface layer 3.5~4.0 wt% The two-layer structure includes a soft layer and a hard layer, and the mass fraction of surface-functionalized sheet-like nanofillers in each layer is: Soft layer 0.5~5.5%; Hard layer 6.0~12.5%; The fluorinated segment is a polyurethane side chain grafted with perfluorooctyl ethyl acrylate. The surface-functionalized sheet nanofiller is a sheet nanofiller treated with a modifier; the sheet nanofiller is one or more composites of montmorillonite, hydrotalcite, or graphene; the modifier is γ-(methacryloyloxy)propyltrimethoxysilane or 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid.

2. The biomimetic composite sealing material for gas storage in abandoned mine tunnels according to claim 1, characterized in that, The total mass parts of each component in the biomimetic composite sealing material are as follows: 30-50 parts of fluorinated segment modified polyether polyurethane, 20-40 parts of polyetheramine modified bisphenol A epoxy resin, 3-8 parts of surface functionalized sheet nanofiller, 2-5 parts of active additives, 0.5-2 parts of anti-aging agent, and 3-6 parts of curing agent.

3. The biomimetic composite sealing material for gas storage in abandoned mine tunnels according to claim 1, characterized in that, The fluorinated segment modified polyether polyurethane has a soft segment to hard segment mass ratio of 1.2 to 1.8:1, and the molar content of the fluorinated segment accounts for 5% to 10% of the polyurethane molecular chain.

4. The biomimetic composite sealing material for gas storage in abandoned mine tunnels according to claim 1, characterized in that, The preparation method of the fluorinated segment modified polyether polyurethane is as follows: polypropylene glycol and 4,4'-diphenylmethane diisocyanate are reacted at 75~85℃, and then 1,4-butanediol is added for chain extension reaction to obtain polyurethane prepolymer; perfluorooctyl ethyl acrylate and azobisisobutyronitrile are mixed and added dropwise to polyurethane prepolymer, and grafting reaction is carried out at 65~75℃.

5. The biomimetic composite sealing material for gas storage in abandoned mine tunnels according to claim 1, characterized in that, In the polyetheramine-modified bisphenol A type epoxy resin, the mass ratio of polyetheramine to epoxy resin is 0.1~0.3:

1.

6. The biomimetic composite sealing material for gas storage in abandoned mine tunnels according to claim 1, characterized in that, The preparation method of the polyetheramine modified bisphenol A epoxy resin is as follows: heat the bisphenol A epoxy resin to 55~65℃, add polyetheramine, and stir and react at 75~85℃.

7. The biomimetic composite sealing material for gas storage in abandoned mine tunnels according to claim 1, characterized in that, The preparation method of the surface-functionalized sheet nanofiller is as follows: the sheet nanofiller is added to anhydrous ethanol and ultrasonically dispersed to form a suspension with a mass concentration of 5% to 10%; a modifier is added at 5% to 10% of the mass of the sheet nanofiller, and the mixture is stirred and reacted at 60 to 80°C.

8. The biomimetic composite sealing material for gas storage in abandoned mine tunnels according to claim 1, characterized in that, The active additive is a bifunctional active additive, which is γ-glycidoxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane; The anti-aging agent is a compound anti-aging agent, which is a compound system of hindered phenolic antioxidants and benzotriazole ultraviolet absorbers, with a mass ratio of 1:1 to 2. The curing agent is a composite curing agent, which is a compound system of isophorone diamine and polyamide resin, with a mass ratio of 2~3:

1.

9. A method for preparing a biomimetic composite sealing material for gas storage in abandoned mine tunnels as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Fluorine-containing segment modified polyether polyurethane and polyetheramine modified bisphenol A epoxy resin are stirred and dispersed evenly at 60~80℃ to obtain a composite matrix; (2) Add surface-functionalized sheet nanofillers and active additives to the composite matrix and disperse them evenly to obtain a filler suspension; prepare corresponding filler suspensions according to the mass fraction of surface-functionalized sheet nanofillers in each layer of the sealing material. (3) Reduce the temperature of the filler suspension to 40~50℃, add anti-aging agent and curing agent, stir and mix evenly to obtain the precursors corresponding to the filler content and each layer of the sealing material; (4) The biomimetic composite sealing material is obtained by using solution casting-gradient molding process or reactive extrusion-laminar composite process, followed by curing and maintenance; The solution casting-gradient molding process is as follows: precursors with filler contents of 3.5~4.0%, 6.5~7.5%, and 3.5~4.0% are cast sequentially from bottom to top into the mold, the solvent is evaporated at 30~50℃, and then solidified to form a three-layer structure; The reactive extrusion-laminar composite process is as follows: the precursor is used to prepare hard layer masterbatch and soft layer masterbatch through a twin-screw extruder, the filler content of the hard layer masterbatch is 6.0~12.5wt%, and the filler content of the soft layer masterbatch is 0.5~5.5wt%; then the hard layer masterbatch and soft layer masterbatch are hot-pressed to form a two-layer structure.

10. The method for preparing the biomimetic composite sealing material for gas storage in abandoned mine roadways according to claim 9, characterized in that, In the three-layer structure, the bottom layer has a thickness of 0.5~1mm, the middle layer has a thickness of 1~2mm, and the top layer has a thickness of 0.5~1mm; in the two-layer structure, the soft layer has a thickness of 1~1.5mm and the hard layer has a thickness of 0.5~1mm.

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