Polyurethane-fly ash composite grouting material for low heat concentration mine based on irreversible phase change and application of polyurethane-fly ash composite grouting material

Abstract

The invention discloses an irreversible-phase-change-based polyurethane-fly ash composite grouting material for a low-heat-concentration mine and application of the irreversible-phase-change-based polyurethane-fly ash composite grouting material, and belongs to the technical field of mining grouting materials, the irreversible-phase-change-based polyurethane-fly ash composite grouting material is composed of a component A and a component B, the component A is 47-75 parts by weight, and the component B is 25-53 parts by weight; the component A is specifically composed of 47 to 73 parts of polyol, 0.2 to 2.0 parts of a catalyst, 0 to 30 parts of fatty acid monoglyceride, 10 to 20 parts of fly ash, 10 to 20 parts of environment-friendly chlorinated paraffin, 5 to 10 parts of a flame retardant, 1 to 5 parts of a silane coupling agent, and 0.1 to 5 parts of an antistatic agent; the component B is specifically prepared from 27 to 53 parts of polyisocyanate. According to the polyurethane-fly ash composite grouting material for the low heat concentration mine based on the irreversible phase change, fatty acid monoglyceride is selected as an organic phase change material, so that active cooling of the composite material is realized by utilizing the high latent heat characteristic of the fatty acid monoglyceride, and the problem of seepage of the phase change material is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mine grouting materials, and particularly to a low-heat mine-used polyurethane-fly ash composite grouting material based on irreversible phase change and its application. Background Art

[0002] Polyurethane grouting materials are widely used in coal mines, construction and other fields for reinforcement due to their good durability, strong adhesion, good permeability, high strength and large expansion rate, and their grouting technology has the advantages of simple operation, easy adjustment of component ratio and adjustable curing time. However, since the main components of ordinary polyurethane grouting materials are isocyanate and polyol, a large amount of heat will be rapidly released during the reaction curing process. Therefore, when using such materials, there are problems such as large heat release during the reaction, high heat storage temperature of the system and poor flame retardant performance of the materials. Especially when used as a reinforcement material in the coal mine field, the internal environment is closed and the heat dissipation condition is poor, which causes the temperature inside the material to rise sharply, and is prone to serious safety hazards such as internal carbonization, smoking, open fire, and local core burning of the material. In order to effectively solve the problem of out-of-control reaction heat of this material, it is imperative to explore new and effective modification methods of polyurethane grouting materials in the fields of controlling reaction heat release and heat storage temperature and improving flame retardant performance.

[0003] At present, there are many means for reducing the heat of polyurethane grouting materials. For the control of reaction heat release, the purpose of reducing reaction heat release can be achieved by changing the amount of catalyst or using a combination of multiple catalysts, preparing prepolymers to release part of the reaction heat in advance, and adjusting the polyether functionality and average hydroxyl value of polyols; for the control of heat storage temperature, the purpose of reducing the reaction temperature can be achieved by introducing self-limiting temperature additives prepared from inorganic hydrated salts, adding high-thermal-conductivity fillers to the polyurethane matrix, and compounding foaming agents, catalysts, solvents and main components, etc. And phase change materials are still a relatively popular means of reducing heat accumulation due to their excellent heat storage performance.

[0004] Phase change materials achieve energy storage and temperature control through the latent heat effect accompanying the phase state transition of substances. However, the existing phase change material systems (including organic phase change materials such as long-chain fatty acids and inorganic phase change materials such as inorganic hydrated salts) have obvious technical bottlenecks: on the one hand, the poor interfacial compatibility between the material and the matrix easily leads to phase separation; on the other hand, the exudation of the liquid phase during the phase change process will cause the attenuation of the material performance, and these problems seriously limit the practical application of phase change materials in the polyurethane field. Although the microcapsule coating technology has made certain breakthroughs in material encapsulation through core-shell structure design, this process still faces the dual challenges of high preparation cost and difficulty in controlling the dispersion uniformity of coated particles in the matrix. Summary of the Invention

[0005] The object of the present invention is to provide a low-thermal polyamine-fly ash composite grouting material based on irreversible phase change and its application. By adding components such as monoglyceride fatty acid to prepare the composite grouting material, active cooling is achieved, and the problem of phase change material exudation is improved. Monoglyceride fatty acid, as a non-paraffin organic phase change material, is a compound formed by the esterification reaction of one hydroxyl group in a glycerol molecule with a single fatty acid, with the chemical general formula CH2(OH)-CH(OH)-CH2-O-COR (R is a fatty acid chain), and its melting point is 60-80°C, which has certain differences due to the different lengths of the fatty acid chains. Such materials have the advantages of high phase change latent heat, good thermal stability, non-toxic and harmless, and non-corrosive to the matrix material. When it is added to the polyurethane system by physical methods, when the reaction temperature during the polyurethane curing process reaches or even exceeds its melting point, solid-liquid phase change will occur, and this process can utilize the latent heat to absorb a large amount of heat released by the system reaction, thereby restricting the increase of the system heat storage temperature. In addition, compared with other organic phase change materials, monoglyceride fatty acid, as a diol, the hydroxyl group at its end can react with the isocyanate group, introducing its lipophilic long-chain alkane into the polyurethane main chain, thereby effectively improving problems such as phase change material exudation and significant decline in high-temperature mechanical properties, so that the material still has good mechanical properties while achieving low thermal aggregation.

[0006] The present invention provides a low-thermal polyamine-fly ash composite grouting material based on irreversible phase change, which consists of two components, A and B. By weight, component A is 47-75 parts, and component B is 25-53 parts;

[0007] The specific composition of component A is: polyol 47-73 parts, catalyst 0.2-2.0 parts, monoglyceride fatty acid 0-30 parts, fly ash 10-20 parts, environmentally friendly chlorinated paraffin 10-20 parts, flame retardant 5-10 parts, silane coupling agent 1-5 parts, antistatic agent 0.1-5 parts;

[0008] The specific composition of component B is: polyisocyanate 27-53 parts.

[0009] Preferably, the polyol is a mixed solution composed of polyether diol and glycerol polyether polyol, and the mass ratio of the polyether diol to the glycerol polyether polyol is (0-1):2.

[0010] Preferably, the catalyst includes dibutyltin dilaurate, triethylenediamine, isooctyltin octoate, N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, butyllithium.

[0011] Preferably, the monoglyceride fatty acid includes monostearin, 1-monopalmitin, myristic acid monoglyceride, lauric acid glyceride, capric acid monoglyceride, caprylic acid monoglyceride.

[0012] Preferably, the flame retardant includes tris(2-chloropropyl) phosphate, tris(2-chloroethyl) phosphate, triisopropylphenyl phosphate, dimethyl methyl phosphate, diethyl ethyl phosphate, and an organic phosphorus flame retardant (model: Doher-6209).

[0013] Preferably, the silane coupling agent includes 3-methacryloxypropyltrimethoxysilane, 3-thiopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, 3-(isomethacryloxy)propyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

[0014] Preferably, the antistatic agent includes polyurethane antistatic agent (model: HW-207), polystyrene sulfonic acid, tris(β-chloroethyl) phosphate, alkyl tertiary amine phosphate, alkyl tertiary amine sulfate, sponge antistatic agent (model: AT-35).

[0015] Preferably, the preparation method of component A comprises the following steps:

[0016] (1) grinding the selected fatty acid monoglyceride for multiple times to obtain fatty acid monoglyceride powder;

[0017] (2) pre-treating fly ash, a silane coupling agent and an ethanol aqueous solution to obtain modified fly ash;

[0018] (3) drying the selected polyol and modified fly ash in a vacuum drying oven for 2 to 3 hours at a temperature of 100 to 120° C.;

[0019] (4) adding the fatty acid monoglyceride powder, modified fly ash, environmentally friendly chlorinated paraffin, flame retardant, silane coupling agent, antistatic agent and catalyst obtained in steps (1), (2) and (3) to the polyol in sequence, stirring thoroughly to obtain a mixed slurry of component A;

[0020] The preparation method of the B component comprises the following steps:

[0021] Weigh a certain amount of polyisocyanate according to the formula and replace it with nitrogen for later use.

[0022] Preferably, the stirring speed in step (4) is 500 to 1000 r / min, and the stirring time is 16 to 24 h.

[0023] Preferably, the application of the low-molecular-weight thermal mining polyurethane-fly ash composite grouting material in underground coal mines comprises the following steps:

[0024] First, determine the construction area, unfold the double-pipe grouting machine and fix it at the target position. Prepare the component A and component B of the polyurethane composite grouting material, put them into their respective pipelines, connect the double-pipe grouting machine and the nozzle, and insert the nozzle into the structure. After starting the grouting machine, the mixer mixes component A and component B and transports them through the nozzle to the position to be sealed and fixed, and forms a filling material after curing; the mixing ratio of component A and component B is 1:1, the injection volume is <50 L / min, the curing time is 100 - 300 s, the main motor power of the double-pipe grouting system is 1 - 2 KW, the grouting pressure is 1.5 - 3 MPa, and the inner diameter of the rubber hose at the slurry outlet is 30 - 50 cm.

[0025] Therefore, the present invention adopts a kind of polyurethane-fly ash composite grouting material based on irreversible phase change and its application with the above structure. By selecting monoglyceride fatty acid as the organic phase change material, not only the active cooling of the composite material is realized by using its high latent heat characteristics, but also the problem of phase change material exudation is effectively improved. The prepared polyurethane / fly ash composite grouting material has the characteristics of small heat release during the curing process, low maximum heat storage temperature, high mechanical strength, good heat resistance, good flame retardant performance and antistatic performance. It is not only suitable for the repair and reinforcement of coal and rock masses and the water inrush plugging in coal mines, but also can be used for the repair of diseases such as collapse, subsidence, cracks and voids in the base course of highway pavements. Moreover, the preparation process is simple, the production cycle is short, the cost is low, and it is environmentally friendly and pollution-free.

[0026] The following will further describe the technical solutions of the present invention in detail through the drawings and embodiments. Brief Description of the Drawings

[0027] Figure 1 It is an infrared thermal imaging diagram of the polyurethane-fly ash composite grouting material for mine use based on irreversible phase change provided by the present invention. Detailed Embodiments

[0028] In order to better understand the above technical solutions, the following will describe the above technical solutions in detail in conjunction with the drawings of the specification and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0029] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms of "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Plural" generally includes at least two.

[0030] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a commodity or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such commodity or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the commodity or device comprising said element.

[0031] The present invention provides a low-temperature heat-mining polyurethane-fly ash composite grouting material based on irreversible phase change, which consists of two components, A and B. By weight, component A is 47 - 75 parts and component B is 25 - 53 parts.

[0032] The specific composition of component A is as follows: polyol 47 - 73 parts, catalyst 0.2 - 2.0 parts, monoglyceride fatty acid 0 - 30 parts, fly ash 10 - 20 parts, environmentally friendly chlorinated paraffin 10 - 20 parts, flame retardant 5 - 10 parts, silane coupling agent 1 - 5 parts, antistatic agent 0.1 - 5 parts.

[0033] The specific composition of component B is: polyisocyanate 27 - 53 parts.

[0034] The polyol is a mixed solution composed of polyether diol and glycerol polyether polyol, and the mass ratio of the polyether diol to the glycerol polyether polyol is (0 - 1):2.

[0035] The catalyst includes dibutyltin dilaurate, triethylenediamine, isooctyltin octoate, N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, butyllithium.

[0036] The monoglyceride fatty acid includes monostearin, 1-monopalmitin, monomyristin, glyceryl laurate, monodecanoin, monooctanoin.

[0037] The flame retardant includes tris(2-chloropropyl) phosphate, tris(2-chloroethyl) phosphate, triisopropylphenyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, organophosphorus flame retardant (model: Doher-6209).

[0038] The silane coupling agent includes 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, 3-aminopropyltriethoxysilane.

[0039] The antistatic agent includes polyurethane antistatic agent (model: HW-207), polystyrene sulfonic acid, tri(β-chloroethyl) phosphate, alkyl tertiary amine phosphate, alkyl tertiary amine sulfate, and sponge antistatic agent (model: AT-35).

[0040] The preparation method of component A comprises the following steps:

[0041] (1) grinding the selected fatty acid monoglyceride for multiple times to obtain fatty acid monoglyceride powder;

[0042] (2) pre-treating fly ash, a silane coupling agent and an ethanol aqueous solution to obtain modified fly ash;

[0043] (3) drying the selected polyol and modified fly ash in a vacuum drying oven for 2 to 3 hours at a temperature of 100 to 120° C.;

[0044] (4) adding the fatty acid monoglyceride powder, modified fly ash, environmentally friendly chlorinated paraffin, flame retardant, silane coupling agent, antistatic agent and catalyst obtained in steps (1), (2) and (3) to the polyol in sequence, stirring thoroughly to obtain a mixed slurry of component A;

[0045] The preparation method of component B comprises the following steps:

[0046] Weigh a certain amount of polyisocyanate according to the formula and replace it with nitrogen for later use.

[0047] The stirring speed in step (4) is 500 to 1000 r / min, and the stirring time is 16 to 24 h.

[0048] The application of low-polyurethane thermal mining-fly ash composite grouting material in coal mines includes the following steps:

[0049] First, determine the construction area, unfold the double-tube grouting machine and fix it at the target position, prepare component A and component B of the polyurethane composite grouting material, put them into their respective pipes, connect the double-tube grouting machine and the nozzle, and insert the nozzle into the structure. After starting the grouting machine, the mixer mixes components A and B and transports them to the position to be sealed through the nozzle, and forms filling material after curing; the ratio of component A to component B is 1:1, the injection volume is <50L / min, the curing time is 100-300s, the main motor power of the double-tube grouting system is 1-2KW, the grouting pressure is 1.5-3MPa, and the inner diameter of the slurry delivery hose is 30-50cm.

[0050] In order to more clearly and in detail introduce the irreversible phase change-based low-molecular thermal mining polyurethane-fly ash composite grouting material and its application provided by the embodiments of the present invention, it will be described in conjunction with specific embodiments below.

[0051] Embodiment 1

[0052] Component A contains 12.1 parts of polyether diol, 30.4 parts of glycerol polyether polyol, 0.2 parts of catalyst dibutyltin dilaurate, and 3.6 parts of stearic acid monoglyceride; component B contains 53.7 parts of isocyanate.

[0053] The selected stearic acid monoglyceride is ground several times to obtain stearic acid monoglyceride powder; the selected polyether diol and glycerol polyether polyol are dried in a vacuum drying oven for 2.5 hours at a temperature of 110°C; the stearic acid monoglyceride powder, polyether diol and glycerol polyether polyol obtained above are mixed and fully stirred to obtain a mixed slurry of component A; the isocyanate is replaced with nitrogen for standby use to obtain component B. The obtained component A and component B are cured in a ratio of 1:1 for 200 seconds.

[0054] Embodiment 2

[0055] Component A comprises 8.1 parts of polyether diol, 30.6 parts of glycerol polyether polyol, 0.2 parts of catalyst dibutyltin dilaurate, and 7.2 parts of stearic acid monoglyceride; component B comprises 53.9 parts of isocyanate.

[0056] The selected stearic acid monoglyceride is ground several times to obtain stearic acid monoglyceride powder; the selected polyether diol and glycerol polyether polyol are dried in a vacuum drying oven for 2.5 hours at a temperature of 110°C; the stearic acid monoglyceride powder, polyether diol and glycerol polyether polyol obtained above are mixed and fully stirred to obtain a mixed slurry of component A; the isocyanate is replaced with nitrogen for standby use to obtain component B. The obtained component A and component B are cured in a ratio of 1:1 for 200 seconds.

[0057] Embodiment 3

[0058] Component A comprises 4.1 parts of polyether diol, 30.7 parts of glycerol polyether polyol, 0.2 parts of catalyst dibutyltin dilaurate, and 10.9 parts of stearic acid monoglyceride; component B comprises 54.1 parts of isocyanate.

[0059] The selected stearic acid monoglyceride is ground several times to obtain stearic acid monoglyceride powder; the selected polyether diol and glycerol polyether polyol are dried in a vacuum drying oven for 2.5 hours at a temperature of 110°C; the stearic acid monoglyceride powder, polyether diol and glycerol polyether polyol obtained above are mixed and fully stirred to obtain a mixed slurry of component A; the isocyanate is replaced with nitrogen for standby use to obtain component B. The obtained component A and component B are cured in a ratio of 1:1 for 200 seconds.

[0060] Embodiment 4

[0061] Component A comprises 30.8 parts of glycerol polyether polyol, 0.2 parts of dibutyltin dilaurate as a catalyst, and 14.7 parts of stearic acid monoglyceride; component B comprises 54.3 parts of isocyanate.

[0062] The selected stearic acid monoglyceride is ground several times to obtain stearic acid monoglyceride powder; the glycerol polyether polyol is dried in a vacuum drying oven for 2.5 hours at a temperature of 110°C; the stearic acid monoglyceride powder and glycerol polyether polyol obtained above are mixed and stirred to obtain a mixed slurry of component A; the isocyanate is replaced with nitrogen for standby use to obtain component B. The obtained component A and component B are cured in a ratio of 1:1 for 200 seconds.

[0063] Embodiment 5

[0064] Component A includes 5.6 parts of polyether diol, 21.4 parts of glycerol polyether polyol, 0.2 parts of catalyst dibutyltin dilaurate, 5.1 parts of stearic acid monoglyceride, 10 parts of fly ash, 10 parts of environmentally friendly chlorinated paraffin, 8 parts of flame retardant tri(2-chloropropyl) phosphate, 1 part of silane coupling agent 3-methacryloxypropyltrimethoxysilane, and 1 part of antistatic agent tri(β-chloroethyl) phosphate; component B includes 37.7 parts of isocyanate.

[0065] The selected stearic acid monoglyceride is ground several times to obtain stearic acid monoglyceride powder; fly ash, silane coupling agent and ethanol aqueous solution are mixed and pretreated to obtain modified fly ash; polyether diol, glycerol polyether polyol and modified fly ash are dried in a vacuum drying oven for 2.5 hours at a temperature of 110°C; the stearic acid monoglyceride powder, modified fly ash, environmentally friendly chlorinated paraffin, flame retardant, silane coupling agent, antistatic agent and catalyst obtained above are added to the polyol in sequence and fully stirred to obtain a mixed slurry of component A; isocyanate is replaced with nitrogen for standby use to obtain component B. The obtained component A and component B are cured in a ratio of 1:1 for 200 seconds.

[0066] Embodiment 6

[0067] Component A includes 2.8 parts of polyether diol, 21.5 parts of glycerol polyether polyol, 0.2 parts of catalyst dibutyltin dilaurate, 7.6 parts of monoglyceride of stearic acid, 10 parts of fly ash, 10 parts of environmentally friendly chlorinated paraffin, 8 parts of flame retardant tri(2-chloropropyl) phosphate, 1 part of silane coupling agent 3-methacryloxypropyltrimethoxysilane, and 1 part of antistatic agent tri(β-chloroethyl) phosphate; component B includes 37.9 parts of isocyanate.

[0068] The selected stearic acid monoglyceride is ground several times to obtain stearic acid monoglyceride powder; fly ash, silane coupling agent and ethanol aqueous solution are mixed and pretreated to obtain modified fly ash; polyether diol, glycerol polyether polyol and modified fly ash are dried in a vacuum drying oven for 2.5 hours at a temperature of 110°C; the stearic acid monoglyceride powder, modified fly ash, environmentally friendly chlorinated paraffin, flame retardant, silane coupling agent, antistatic agent and catalyst obtained above are added to the polyol in sequence and fully stirred to obtain a mixed slurry of component A; isocyanate is replaced with nitrogen for standby use to obtain component B. The obtained component A and component B are cured in a ratio of 1:1 for 200 seconds.

[0069] Embodiment 7

[0070] Component A includes 4.0 parts of polyether diol, 15.3 parts of glycerol polyether polyol, 0.2 parts of catalyst dibutyltin dilaurate, 3.6 parts of monoglyceride of stearic acid, 20 parts of fly ash, 20 parts of environmentally friendly chlorinated paraffin, 8 parts of flame retardant tri(2-chloropropyl) phosphate, 1 part of silane coupling agent 3-methacryloxypropyltrimethoxysilane, and 1 part of antistatic agent tri(β-chloroethyl) phosphate; component B includes 26.9 parts of isocyanate.

[0071] The selected stearic acid monoglyceride is ground several times to obtain stearic acid monoglyceride powder; fly ash, silane coupling agent and ethanol aqueous solution are mixed and pretreated to obtain modified fly ash; polyether diol, glycerol polyether polyol and modified fly ash are dried in a vacuum drying oven for 2.5 hours at a temperature of 110°C; the stearic acid monoglyceride powder, modified fly ash, environmentally friendly chlorinated paraffin, flame retardant, silane coupling agent, antistatic agent and catalyst obtained above are added to the polyol in sequence and fully stirred to obtain a mixed slurry of component A; isocyanate is replaced with nitrogen for standby use to obtain component B. The obtained component A and component B are cured in a ratio of 1:1 for 200 seconds.

[0072] Embodiment 8

[0073] Component A includes 2.0 parts of polyether diol, 15.4 parts of glycerol polyether polyol, 0.2 parts of catalyst dibutyltin dilaurate, 5.4 parts of stearic acid monoglyceride, 20 parts of fly ash, 20 parts of environmentally friendly chlorinated paraffin, 8 parts of flame retardant tri(2-chloropropyl) phosphate, 1 part of silane coupling agent 3-methacryloxypropyltrimethoxysilane, and 1 part of antistatic agent tri(β-chloroethyl) phosphate; component B includes 27 parts of isocyanate.

[0074] The selected stearic acid monoglyceride is ground several times to obtain stearic acid monoglyceride powder; fly ash, silane coupling agent and ethanol aqueous solution are mixed and pretreated to obtain modified fly ash; polyether diol, glycerol polyether polyol and modified fly ash are dried in a vacuum drying oven for 2.5 hours at a temperature of 110°C; the stearic acid monoglyceride powder, modified fly ash, environmentally friendly chlorinated paraffin, flame retardant, silane coupling agent, antistatic agent and catalyst obtained above are added to the polyol in sequence and fully stirred to obtain a mixed slurry of component A; isocyanate is replaced with nitrogen for standby use to obtain component B. The obtained component A and component B are cured in a ratio of 1:1 for 200 seconds.

[0075] Comparative Example

[0076] Component A contains 16.8 parts of polyether diol, 30 parts of glycerol polyether polyol, and 0.2 parts of dibutyltin dilaurate as a catalyst; component B contains 53 parts of isocyanate.

[0077] The selected polyether diol and glycerol polyether polyol were dried in a vacuum drying oven for 2.5 hours at a temperature of 110°C; the catalyst dibutyltin dilaurate, polyether diol and glycerol polyether polyol obtained above were mixed and stirred thoroughly to obtain a mixed slurry of component A; the isocyanate was replaced with nitrogen for standby use to obtain component B. The obtained component A and component B were cured in a ratio of 1:1 for 200 seconds.

[0078] Table 1 The amount of each component required for preparing polyurethane composite grouting material

[0079]

[0080]

[0081] For the highest reaction temperature, the addition of monoglyceride stearate, modified fly ash, and environmentally friendly chlorinated paraffin decreases the highest reaction temperature during the curing process. The first step of temperature reduction: There is a fatty acid phase change material in the system. When the system reaches the temperature at which the phase change occurs, this phase change material will undergo a solid-liquid phase change. This process can utilize the latent heat to absorb a large amount of heat released by the system reaction, thereby restricting the increase in the heat storage temperature of the system. Specifically, the temperature at which monoglyceride stearate undergoes a phase change is 60 - 80°C. During the curing process, the temperature of the polyurethane reaction system gradually increases. When it reaches its phase change temperature, monoglyceride stearate melts, and this process absorbs a part of the heat released by the polyurethane curing reaction, thereby achieving the purpose of reducing the reaction temperature. The second step of temperature reduction: When components A and B are mixed and stirred, the nano fly ash particles can be quickly wrapped by the organic reaction solution and evenly dispersed in the reaction system. By means of heat conduction, a part of the heat is absorbed from the inside of the organic reactants, thereby achieving the purpose of reducing the reaction temperature. The third step of temperature reduction: Environmentally friendly chlorinated paraffin, as an alkane chlorinated derivative, has certain chemical inertness. When components A and B are mixed and stirred, it can be evenly dispersed in the organic reaction solution. During the heating process, a part of the heat is absorbed from the inside of the organic reactants by means of heat conduction, thereby achieving the purpose of reducing the reaction temperature. The highest reaction temperatures of the comparative samples and examples are shown in Table 2, and the heat release amounts during the reaction process are shown in Table 3. It can be seen that compared with the comparative samples, the highest reaction temperature of Example 4 decreased by as much as 27°C, and the highest reaction temperature of Example 8 decreased by as much as 47°C, showing a significant temperature reduction effect.

[0082] Table 2 The highest reaction temperatures of polyurethane composite grouting materials

[0083]

[0084] Table 3 The heat release amounts during the reaction process of polyurethane composite grouting materials

[0085]

[0086]

[0087] For mechanical properties, on the one hand, after fly ash is modified by 3-methacryloxypropyltrimethoxysilane (MPS) silane coupling agent, the alkoxy groups in the MPS molecules can be fully hydrolyzed and associate with each other to form silanol molecules covering the surface of fly ash. While promoting its surface organicization, it acts as a "bridge" to connect the organic matrix polyurethane, forming a relatively firm interfacial layer between the two phases of fly ash-organic reactants, further promoting the more uniform distribution of fly ash particles in the polyurethane matrix, thereby increasing the crosslinking density of the composite material and raising the mechanical strength. On the other hand, monoglyceride stearate, as a diol, undergoes a chemical reaction with the isocyanate group through its terminal active hydroxyl group, introducing its lipophilic long alkane chain into the polyurethane main chain. This not only overcomes the defect that traditional phase change materials are prone to exudation but also improves the phase separation problem caused by poor interfacial compatibility between the phase change material and the matrix, thus significantly inhibiting the deterioration trend of the mechanical properties of the material. Compared with traditional organic phase change materials, it fundamentally solves the contradiction between low reaction temperature and high mechanical strength, enabling the composite system to maintain a relatively high mechanical strength while achieving low heat of polymerization, providing new ideas for the development of high-performance phase change polyurethane composite grouting materials. The compressive strengths of the comparative samples and examples are shown in Table 4:

[0088] Table 4 Compressive Strength of Polyurethane Composite Grouting Material

[0089]

[0090]

[0091] In terms of high-temperature stability, monoglyceride stearate, as a solid phase change material, realizes its uniform dispersion in the matrix by actively participating in the polyurethane curing and crosslinking reaction. More importantly, due to the irreversible phase change of monoglyceride stearate during the curing process, there will be no liquefaction and exudation problems even in a high-temperature environment, and this characteristic significantly improves the high-temperature mechanical properties of the material. In this invention, monoglyceride stearate and polyurethane are compounded, and the compressive strengths at different temperatures are tested. As shown in Table 5, it can be seen that in a high-temperature environment of 60 °C, the compressive strength of Example 2 is still 54.7 MPa, and the composite material still maintains good mechanical properties and has excellent heat resistance characteristics.

[0092] Table 5 Compressive Strength of Polyurethane Composite Grouting Material at Different Temperatures

[0093]

[0094] In terms of flame retardancy, for the addition of modified fly ash and environmentally friendly chlorinated paraffin, their flame retardant mechanism lies in that the two can adhere evenly to the matrix of the polyurethane grouting material, playing an insulating role, capturing combustible gases as spherical particles, blocking the propagation and diffusion of heat and gas, and preventing the pyrolysis products from overflowing; for the addition of tris(2-chloropropyl) phosphate (TCPP) flame retardant, its flame retardant mechanism lies in that TCPP can thermally decompose into phosphoric acid or polyphosphoric acid in the condensed phase, and these phosphoric acids can generate a molten viscous surface layer to protect the polymer matrix from burning or oxidizing. For example, the phosphorus compounds generated by the decomposition of TCPP react with the surface of the polyurethane material at high temperature to form a carbon layer, and the carbon itself is difficult to burn and isolates the polyurethane material matrix from heat, fire and oxygen; TCPP can also inhibit combustion through gas-phase reactions. When the polyurethane material burns, it can form a molten glassy substance on the surface of the polyurethane to play the role of a mass and heat transfer barrier layer. Therefore, the addition of the above three substances endows the polyurethane grouting material with good flame retardancy. The oxygen index of the comparative sample in the present invention is 26%, and the oxygen indexes of Example 6 and Example 8 are 28% and 28.5% respectively, both of which can reach the non-flammable level.

[0095] In terms of antistatic property, tris(β-chloroethyl) phosphate (TCEP) is a surfactant. Its main advantages are good compatibility with the polyurethane matrix, strong interfacial adhesion, high flash point and low toxicity. TCEP has the ability to continuously migrate to the surface of the polymer. On the surface of the polyurethane material, the lipophilic groups in the molecule are generally easy to combine with the polymer, and the hydrophilic groups are on the surface of the polymer, forming a water film with a hygroscopic effect. This water film is arranged facing the air, providing certain conditions for the conduction of charges to the air. In addition, the smoothness of TCEP will reduce the friction coefficient on the surface of the polyurethane material, thereby reducing the possibility of static charge accumulation and improving the antistatic performance of the polyurethane grouting material.

[0096] Therefore, the present invention adopts a low-temperature heat storage mining polyurethane-fly ash composite grouting material based on irreversible phase change and its application with the above structure. By selecting monoglyceride fatty acid as the organic phase change material, not only the active cooling of the composite material is realized by using its high latent heat characteristics, but also the problem of phase change material exudation is effectively improved. The prepared polyurethane / fly ash composite grouting material has the characteristics of small heat release during the curing process, low maximum heat storage temperature, high mechanical strength, good temperature resistance, good flame retardancy and antistatic performance. It is not only suitable for the repair and reinforcement of coal and rock masses and the water inrush plugging in coal mines, but also can be used for the repair of diseases such as collapse, subsidence, cracks and voids in the base layer of highway pavements. Moreover, the preparation process is simple, the production cycle is short, the cost is low, and it is environmentally friendly and pollution-free.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A low-molecular thermal mining polyurethane-fly ash composite grouting material based on irreversible phase change, characterized in that: It is composed of two components, A and B, with 47-75 parts of component A and 25-53 parts of component B by weight. The specific composition of the A component is: 47-73 parts of polyol, 0.2-2.0 parts of catalyst, 0-30 parts of fatty acid monoglyceride, 10-20 parts of fly ash, 10-20 parts of environmentally friendly chlorinated paraffin, 5-10 parts of flame retardant, 1-5 parts of silane coupling agent, and 0.1-5 parts of antistatic agent; The specific composition of the B component is: 27 to 53 parts of polyisocyanate.

2. The irreversible phase change-based oligomeric thermal mining polyurethane-fly ash composite grouting material according to claim 1, characterized in that: The polyol is a mixed solution of polyether diol and glycerol polyether polyol, and the mass ratio of the polyether diol to the glycerol polyether polyol is (0-1):

2.

3. The irreversible phase change-based oligomeric thermal mining polyurethane-fly ash composite grouting material according to claim 1, characterized in that: The catalyst includes dibutyltin dilaurate, triethylenediamine, isotin octoate, N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether and butyl lithium.

4. The irreversible phase change-based low-molecular thermal mining polyurethane-fly ash composite grouting material according to claim 1, characterized in that: The fatty acid monoglycerides include stearic acid monoglyceride, 1-palmitic acid monoglyceride, myristic acid monoglyceride, lauric acid glyceride, monocapric acid glyceride, and monocaprylic acid glyceride.

5. The irreversible phase change-based low-molecular thermal mining polyurethane-fly ash composite grouting material according to claim 1, characterized in that: The flame retardant includes tris(2-chloropropyl)phosphate, tris(2-chloroethyl)phosphate, triisopropylphenyl phosphate, dimethyl methyl phosphate, diethyl ethyl phosphate, and organic phosphorus flame retardant.

6. The irreversible phase change-based low-molecular thermal mining polyurethane-fly ash composite grouting material according to claim 1, characterized in that: The silane coupling agent includes 3-methacryloxypropyltrimethoxysilane, 3-thiopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, 3-(isomethacryloxy)propyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

7. The irreversible phase change-based low-molecular thermal mining polyurethane-fly ash composite grouting material according to claim 1, characterized in that: The antistatic agent includes polyurethane antistatic agent, polystyrene sulfonic acid, tris(β-chloroethyl) phosphate, alkyl tertiary amine phosphate, alkyl tertiary amine sulfate, and sponge antistatic agent.

8. The irreversible phase change-based low-molecular thermal mining polyurethane-fly ash composite grouting material according to claim 1, characterized in that: The preparation method of component A comprises the following steps: (1) grinding the selected fatty acid monoglyceride for multiple times to obtain fatty acid monoglyceride powder; (2) pre-treating fly ash, a silane coupling agent and an ethanol aqueous solution to obtain modified fly ash; (3) drying the selected polyol and modified fly ash in a vacuum drying oven for 2 to 3 hours at a temperature of 100 to 120° C.; (4) adding the fatty acid monoglyceride powder, modified fly ash, environmentally friendly chlorinated paraffin, flame retardant, silane coupling agent, antistatic agent and catalyst obtained in steps (1), (2) and (3) to the polyol in sequence, stirring thoroughly to obtain a mixed slurry of component A; The preparation method of the B component comprises the following steps: Weigh a certain amount of polyisocyanate according to the formula and replace it with nitrogen for later use.

9. The irreversible phase change-based low-molecular thermal mining polyurethane-fly ash composite grouting material according to claim 8, characterized in that: The stirring speed in step (4) is 500-1000 r / min, and the stirring time is 16-24 h.

10. An application of the low-molecular-weight thermal mining polyurethane-fly ash composite grouting material according to any one of claims 1 to 9 in underground coal mines, characterized in that: The application method includes the following steps: First, determine the construction area, unfold the double-tube grouting machine and fix it at the target position, prepare component A and component B of the polyurethane composite grouting material, put them into their respective pipes, connect the double-tube grouting machine and the nozzle, and insert the nozzle into the structure. After starting the grouting machine, the mixer mixes components A and B and transports them to the position to be sealed through the nozzle, and forms filling material after curing; the ratio of component A to component B is 1:1, the injection volume is <50L / min, the curing time is 100-300s, the main motor power of the double-tube grouting system is 1-2KW, the grouting pressure is 1.5-3MPa, and the inner diameter of the slurry delivery hose is 30-50cm.

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