Preparation process of high polymer coal spontaneous combustion inhibitor

Abstract

The invention relates to the technical field of inhibitors, and discloses a preparation process of a high polymer coal spontaneous combustion inhibitor. The process comprises the following steps: S1, uniformly dispersing polydopamine microcapsules in deionized water, adding GMA (glycidyl methacrylate) grafted CNC (computer numerical control), and uniformly stirring to obtain a mixed solution; s2, sequentially adding acrylic acid and acrylamide into the mixed solution prepared in the step S1, then adding a cross-linking agent and an initiator, stirring under the protection of nitrogen, reacting to form gel, soaking the gel into ethanol to replace moisture, and freeze-drying to obtain the stopping agent. According to the preparation process, the thermal stability and the inhibition effect of the inhibitor are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inhibitor agents, and particularly to a preparation process of a high-polymer coal spontaneous combustion inhibitor agent. Background Art

[0002] Coal spontaneous combustion is a common safety hazard during coal mining, storage, and transportation. It not only causes waste of coal resources but also poses a serious threat to the environment and human health. According to statistics, approximately 80% of the mined coal seams in China have a high tendency of spontaneous combustion, and coal spontaneous combustion problems basically exist in mines that mine thick coal seams. Toxic and harmful gases such as CO and SO2 generated by coal spontaneous combustion pose a serious threat to the physical and mental health of personnel and may even trigger major and extremely serious accidents such as gas and coal dust explosions. In addition, coal spontaneous combustion also causes damage to coal resources and ecological environment. Especially in the northwest region of China, large areas of coalfield spontaneous combustion areas have brought very serious environmental problems.

[0003] Coal spontaneous combustion is a complex physical and chemical process involving multiple factors such as the chemical composition, physical structure, and environmental conditions of coal. Combustible substances such as carbon, sulfur, and nitrogen in coal will react with oxygen under specific conditions to generate heat. When the heat accumulates to a certain extent, the temperature of the coal body rises, further accelerating the progress of the chemical reaction. This self-heating process continuously cycles, ultimately leading to the spontaneous combustion of coal. The kinetic mechanism of coal spontaneous combustion includes key links such as heat generation and accumulation, heat transfer path and speed, and temperature distribution and change inside the coal body.

[0004] A high-polymer coal spontaneous combustion inhibitor agent is an inhibitor agent prepared using high-molecular polymer materials, which mainly inhibits coal spontaneous combustion through physical and chemical actions. High-polymer inhibitor agents usually consist of high polymers, special surfactants, and a small amount of additives. These components can interact with each other to form an inhibitor system with a stable structure and excellent performance.

[0005] Although high-polymer coal spontaneous combustion inhibitor agents have shown good application prospects in the prevention and control of coal spontaneous combustion, existing high-polymer coal spontaneous combustion inhibitor agents still have some problems, which limit their effects and popularization in practical applications. As the coal temperature rises, high-polymer inhibitor agents are prone to thermal decomposition, thus losing their inhibition effect. At the same time, combustible gases may be released during the thermal decomposition process, increasing the risk of coal spontaneous combustion. For example, some high-polymer inhibitor agents will decompose to produce small-molecule compounds at high temperatures. These small-molecule compounds not only cannot continue to play an inhibition role but may also become combustion promoters for coal spontaneous combustion. The inhibition efficiency of some high-polymer inhibitor agents during coal spontaneous combustion is relatively low, and they cannot effectively inhibit the process of coal spontaneous combustion. This may be due to the insufficient binding force between the inhibitor agent and the coal body surface or the inability of the active ingredients in the inhibitor agent to fully penetrate into the coal body, resulting in limited inhibition effects. Based on this, the present invention provides a preparation process of a high-polymer coal spontaneous combustion inhibitor agent. Summary of the Invention

[0006] In order to solve the problems mentioned in the above background art, the present invention provides a preparation process of a high-polymer coal spontaneous combustion inhibitor.

[0007] The present invention adopts the following technical solutions:

[0008] A preparation process of a high-polymer coal spontaneous combustion inhibitor includes the following steps:

[0009] S1. Disperse polydopamine microcapsules evenly in deionized water, add CNC grafted with GMA, and stir until uniform to obtain a mixed solution;

[0010] S2. Sequentially add acrylic acid and acrylamide to the mixed solution prepared in step S1, then add a crosslinking agent and an initiator, stir under nitrogen protection, form a gel after reaction, immerse the gel in ethanol to displace water, and obtain the high-polymer coal spontaneous combustion inhibitor after freeze-drying.

[0011] Further, the weight part ratio of the polydopamine microcapsules, deionized water, CNC grafted with GMA, acrylic acid, acrylamide, crosslinking agent and initiator is (3 - 5):(50 - 60):(4 - 5):(14 - 16):(4 - 6):(0.5 - 0.7):(1 - 1.4).

[0012] Further, the preparation method of the polydopamine microcapsules includes the following steps: Mix paraffin and stearic acid, melt and stir to form a homogeneous complex, cool to room temperature, crush into powder for standby; Dissolve the homogeneous complex powder in ethanol, add it to an aqueous solution of sodium dodecyl sulfate, ultrasonically emulsify to form an O / W emulsion, add a dopamine hydrochloride solution to the emulsion, stir, centrifuge, wash and dry to obtain.

[0013] Further, the weight part ratio of the paraffin and stearic acid is (6 - 7):(3 - 4).

[0014] Further, the concentration of the aqueous solution of sodium dodecyl sulfate is 0.5 - 1 g / 100 mL; the concentration of the dopamine hydrochloride aqueous solution is 2 - 3 mg / mL; the dosage ratio of the homogeneous complex powder, ethanol, aqueous solution of sodium dodecyl sulfate and dopamine hydrochloride aqueous solution is (1 - 2) g:(10 - 20) mL:(100 - 110) mL:(85 - 95) mL.

[0015] Further, the preparation method of the CNC grafted with GMA includes the following steps: Disperse cellulose nanocrystals (CNC) in deionized water, add glycidyl methacrylate (GMA), react at 60 - 70 °C for 6 - 8 hours, and obtain after centrifuging and washing.

[0016] Furthermore, the dosage ratio of the cellulose nanocrystals, deionized water and glycidyl methacrylate is (5 - 7) g : (100 - 110) mL : (2 - 3) g.

[0017] Furthermore, the diameter of the cellulose nanocrystals is 10 - 20 nm, and the length is 100 - 300 nm.

[0018] Furthermore, the crosslinking agent is N,N'-methylenebisacrylamide; the initiator is ammonium persulfate.

[0019] Furthermore, the freeze-drying temperature is -45 to -55 °C, and the time is 24 - 26 h.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The present invention uses polydopamine microcapsules as the core functional unit of the inhibitor. By encapsulating the paraffin / stearic acid phase change material, it realizes the dual mechanisms of endothermic phase change and carbonization barrier to inhibit coal spontaneous combustion. Among them, paraffin and stearic acid are used as phase change materials, which absorb heat during the process of coal spontaneous combustion and reduce the temperature of the coal body. The polydopamine microcapsules serve as the encapsulation layer, which not only protects the phase change material from the external environment, but also forms a barrier layer by carbonization at high temperatures, preventing the direct contact between oxygen and the coal body, thereby effectively inhibiting coal spontaneous combustion. The experimental results of Comparative Example 1 show that the CO concentration increases significantly, verifying the importance of the microcapsules.

[0022] In the present invention, the grafting of GMA onto CNC enhances the crosslinking density of the gel network, improving the thermal stability and mechanical strength of the inhibitor. Among them, the grafting of GMA onto CNC forms a stronger interfacial bond with the polymer network, increasing the crosslinking points of the gel network, thereby improving the overall strength and stability of the inhibitor. The experimental results of Comparative Example 2 (without grafting CNC) show that the CO concentration increases, indicating the enhancing effect of the grafting of GMA onto CNC on the inhibition performance.

[0023] The choice of crosslinking agent in the present invention directly affects the thermal stability of the inhibitor. N,N'-methylenebisacrylamide is superior to ethylene glycol dimethacrylate. Among them, N,N'-methylenebisacrylamide as the crosslinking agent can form a more stable crosslinked structure, improving the thermal stability of the inhibitor. The experimental results of Comparative Example 3 show that the initial decomposition temperature and char residue rate of the inhibitor using ethylene glycol dimethacrylate as the crosslinking agent are both lower than those of the inhibitor using N,N'-methylenebisacrylamide.

[0024] In the present invention, the freeze-drying temperature needs to be controlled at -45 to -55 °C to ensure the uniformity of the porous structure. Freeze-drying at -45 to -55 °C can form a more uniform and finer porous structure, which is beneficial to the penetration and coverage of the inhibitor. The experimental results of Comparative Example 5 show that the inhibitor obtained by low-temperature freeze-drying has better performance.

[0025] In the present invention, by optimizing the ratio of acrylic acid and acrylamide, the stability of the gel network is enhanced. Acrylamide forms a stronger network structure with monomers such as acrylic acid through hydrogen bonds, improving the stability and inhibition performance of the inhibitor. The experimental results of Comparative Example 6 show that the inhibitor without acrylamide has poor performance. Specific Embodiments

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market.

[0028] Among them, paraffin wax: CAS number: 64742-51-4, purchased from Jinan Dehou Chemical Co., Ltd.

[0029] Example 1

[0030] A preparation process of a high-polymer coal spontaneous combustion inhibitor includes the following steps:

[0031] (1) Preparation of polydopamine microcapsules: Mix paraffin wax and stearic acid and melt them under stirring at 75 °C for 1 h to form a homogeneous complex. Cool to room temperature and crush into powder for standby; Dissolve the homogeneous complex powder in ethanol, add it to an aqueous solution of sodium dodecyl sulfate with a concentration of 0.7 g / 100 mL, and emulsify it into an O / W emulsion by ultrasonic treatment at a power of 300 W for 30 min. Adjust the pH of the emulsion to 8.5, add an aqueous solution of dopamine hydrochloride with a concentration of 2.5 mg / mL to the emulsion, stir at 200 rpm for 24 h, then centrifuge at 8000 rpm for 10 min, wash 3 times with deionized water, and dry at 60 °C for 24 h to obtain; The weight ratio of paraffin wax to stearic acid is 6.5:3.5; The dosage ratio of the homogeneous complex powder, ethanol, aqueous solution of sodium dodecyl sulfate and aqueous solution of dopamine hydrochloride is 1.5 g:15 mL:105 mL:90 mL;

[0032] (2) The preparation method of GMA-grafted CNC includes the following steps: Dispersing cellulose nanocrystals (CNC) in deionized water, adding glycidyl methacrylate (GMA), reacting at 65 °C for 7 hours, and the dosage ratio of cellulose nanocrystals, deionized water and glycidyl methacrylate is 6 g: 105 mL: 2.5 g; centrifuging at 6000 rpm for 10 min, washing with deionized water, and drying at 50 °C to obtain; the average diameter of cellulose nanocrystals is 15 nm, and the average length is 200 nm;

[0033] (3) Disperse the polydopamine microcapsules in deionized water and ultrasonically treat them for 30 min at a power of 200 W until evenly dispersed. Add GMA-grafted CNC and stir at 300 rpm until homogeneous to obtain a mixed solution; sequentially add acrylic acid and acrylamide to the prepared mixed solution, then add the cross-linking agent N,N'-methylenebisacrylamide and the initiator ammonium persulfate, and magnetically stir at 60 °C and a rotation speed of 200 rpm for 3 hours under nitrogen protection. After the reaction, adjust the pH of the system to 7.0 with a 10% NaOH aqueous solution by mass concentration, let it stand for 20 h to form a gel, immerse the gel in ethanol to displace the water, and freeze-dry at -50 °C for 25 h to obtain the inhibitor; the weight part ratio of polydopamine microcapsules, deionized water, GMA-grafted CNC, acrylic acid, acrylamide, cross-linking agent and initiator is 4:55:4.5:15:5:0.6:1.2.

[0034] Example 2

[0035] A preparation process of a polymer coal spontaneous combustion inhibitor includes the following steps:

[0036] (1) Preparation of polydopamine microcapsules: Mix paraffin and stearic acid and melt and stir at 75 °C for 1 h to form a homogeneous complex. Cool to room temperature and crush into powder for later use; dissolve the homogeneous complex powder in ethanol, add an aqueous solution of sodium dodecyl sulfate with a concentration of 0.5 g / 100 mL, ultrasonically emulsify at a power of 300 W for 30 min to form an O / W emulsion, adjust the pH of the emulsion to 8.5, add an aqueous solution of dopamine hydrochloride with a concentration of 2 mg / mL to the emulsion, stir at 200 rpm for 24 h, then centrifuge at 8000 rpm for 10 min, wash with deionized water 3 times, and dry at 60 °C for 24 h to obtain; the weight part ratio of paraffin and stearic acid is 6:4; the dosage ratio of the homogeneous complex powder, ethanol, aqueous solution of sodium dodecyl sulfate and aqueous solution of dopamine hydrochloride is 1 g: 10 mL: 100 mL: 85 mL;

[0037] (2) The preparation method of GMA-grafted CNC includes the following steps: Dispersing cellulose nanocrystals in deionized water, adding glycidyl methacrylate, and reacting at 60 °C for 6 hours. The dosage ratio of cellulose nanocrystals, deionized water, and glycidyl methacrylate is 5 g: 100 mL: 2 g; centrifuging at 6000 rpm for 10 min, washing with deionized water, and drying at 50 °C to obtain; the average diameter of cellulose nanocrystals is 10 nm, and the average length is 100 nm;

[0038] (3) Disperse the polydopamine microcapsules in deionized water and ultrasonically treat them for 30 min at a power of 200 W until evenly dispersed. Add GMA-grafted CNC and stir at 300 rpm until uniform to obtain a mixed solution; successively add acrylic acid and acrylamide to the prepared mixed solution, then add the cross-linking agent N,N'-methylenebisacrylamide and the initiator ammonium persulfate, and magnetically stir at 60 °C and a rotation speed of 200 rpm for 3 hours under nitrogen protection. After the reaction, adjust the pH of the system to 7.0 with a 10% NaOH aqueous solution by mass concentration, let it stand for 20 h to form a gel, immerse the gel in ethanol to displace the water, and freeze-dry at -45 °C for 24 h to obtain the inhibitor; the weight part ratio of polydopamine microcapsules, deionized water, GMA-grafted CNC, acrylic acid, acrylamide, cross-linking agent, and initiator is 3: 50: 4: 14: 4: 0.5: 1.

[0039] Example 3

[0040] A preparation process of a high-polymer coal spontaneous combustion inhibitor includes the following steps:

[0041] (1) Preparation of polydopamine microcapsules: Mix paraffin and stearic acid and melt and stir at 75 °C for 1 h to form a homogeneous complex. Cool to room temperature and crush into powder for later use; dissolve the homogeneous complex powder in ethanol, add an aqueous solution of sodium dodecyl sulfate with a concentration of 1 g / 100 mL, ultrasonically emulsify at a power of 300 W for 30 min to form an O / W emulsion, adjust the pH of the emulsion to 8.5, add an aqueous solution of dopamine hydrochloride with a concentration of 3 mg / mL to the emulsion, stir at 200 rpm for 24 h, then centrifuge at 8000 rpm for 10 min, wash 3 times with deionized water, and dry at 60 °C for 24 h to obtain; the weight part ratio of paraffin and stearic acid is 7: 3; the dosage ratio of the homogeneous complex powder, ethanol, aqueous solution of sodium dodecyl sulfate, and aqueous solution of dopamine hydrochloride is 2 g: 20 mL: 110 mL: 95 mL;

[0042] (2) The preparation method of GMA-grafted CNC includes the following steps: Disperse cellulose nanocrystals in deionized water, add glycidyl methacrylate, and react at 70 °C for 8 hours. The dosage ratio of cellulose nanocrystals, deionized water, and glycidyl methacrylate is 7 g: 110 mL: 3 g; Centrifuge at 6000 rpm for 10 min, wash with deionized water, and dry at 50 °C to obtain; The average diameter of cellulose nanocrystals is 20 nm, and the average length is 300 nm;

[0043] (3) Disperse polydopamine microcapsules in deionized water and ultrasonically treat for 30 min at a power of 200 W until evenly dispersed. Add GMA-grafted CNC and stir at 300 rpm until uniform to obtain a mixed solution; Add acrylic acid and acrylamide to the prepared mixed solution in sequence, then add crosslinking agent N,N'-methylenebisacrylamide and initiator ammonium persulfate, and magnetically stir at 60 °C and a rotation speed of 200 rpm for 3 hours under nitrogen protection. After the reaction, adjust the pH of the system to 7.0 with a 10% NaOH aqueous solution by mass concentration, let it stand for 20 h to form a gel, immerse the gel in ethanol to displace the water, and freeze-dry at -55 °C for 26 h to obtain the inhibitor; The weight part ratio of polydopamine microcapsules, deionized water, GMA-grafted CNC, acrylic acid, acrylamide, crosslinking agent, and initiator is 5: 60: 5: 16: 6: 0.7: 1.4.

[0044] Example 4

[0045] A preparation process of a polymer coal spontaneous combustion inhibitor includes the following steps:

[0046] (1) Preparation of polydopamine microcapsules: Mix paraffin and stearic acid and melt and stir at 75 °C for 1 h to form a homogeneous complex. Cool to room temperature and crush into powder for standby; Dissolve the homogeneous complex powder in ethanol, add an aqueous solution of sodium dodecyl sulfate with a concentration of 0.5 g / 100 mL, and ultrasonically emulsify at a power of 300 W for 30 min to form an O / W emulsion. Adjust the pH of the emulsion to 8.5, add an aqueous solution of dopamine hydrochloride with a concentration of 3 mg / mL to the emulsion, stir at 200 rpm for 24 h, then centrifuge at 8000 rpm for 10 min, wash with deionized water 3 times, and dry at 60 °C for 24 h to obtain; The weight part ratio of paraffin and stearic acid is 6: 4; The dosage ratio of the homogeneous complex powder, ethanol, aqueous solution of sodium dodecyl sulfate, and aqueous solution of dopamine hydrochloride is 1 g: 10 mL: 110 mL: 95 mL;

[0047] (2) The preparation method of GMA-grafted CNC includes the following steps: Dispersing cellulose nanocrystals in deionized water, adding glycidyl methacrylate, reacting at 70 °C for 6 hours, and the dosage ratio of cellulose nanocrystals, deionized water and glycidyl methacrylate is 5 g: 110 mL: 3 g; centrifuging at 6000 rpm for 10 min, washing with deionized water, and drying at 50 °C to obtain; the average diameter of cellulose nanocrystals is 10 nm and the average length is 300 nm;

[0048] (3) Disperse the polydopamine microcapsules in deionized water and ultrasonically treat them for 30 min at a power of 200 W until evenly dispersed. Add GMA-grafted CNC and stir at 300 rpm until evenly mixed to obtain a mixed solution; sequentially add acrylic acid and acrylamide to the prepared mixed solution, and then add the crosslinking agent N,N'-methylenebisacrylamide and the initiator ammonium persulfate. Under nitrogen protection, magnetically stir at 60 °C and a rotation speed of 200 rpm for 3 hours. After the reaction, adjust the pH of the system to 7.0 with a 10% NaOH aqueous solution, let it stand for 20 h to form a gel, immerse the gel in ethanol to displace the water, and freeze-dry at -55 °C for 24 h to obtain the inhibitor; the weight ratio of polydopamine microcapsules, deionized water, GMA-grafted CNC, acrylic acid, acrylamide, crosslinking agent and initiator is 3: 60: 4: 16: 4: 0.7: 1.

[0049] Comparative Example 1

[0050] Based on Example 1 with adjustments, different from Example 1, in Comparative Example 1, polydopamine microcapsules are not added.

[0051] Comparative Example 2

[0052] Based on Example 1 with adjustments, different from Example 1, in Comparative Example 2, unmodified cellulose nanocrystals (i.e., not grafted with glycidyl methacrylate) are used.

[0053] Comparative Example 3

[0054] Based on Example 1 with adjustments, different from Example 1, in Comparative Example 3, in step 3, the crosslinking agent is changed to ethylene glycol dimethacrylate (replacing N,N'-methylenebisacrylamide).

[0055] Comparative Example 4

[0056] Based on Example 1 with adjustments, different from Example 1, in Comparative Example 4, GMA-grafted CNC is not added.

[0057] Comparative Example 5

[0058] Based on Example 1 with adjustments, different from Example 1, in Comparative Example 5, the freeze-drying temperature in Step 3 was adjusted to -30°C.

[0059] Comparative Example 6

[0060] Based on Example 1 with adjustments, different from Example 1, in Comparative Example 6, acrylamide was not added in Step 3, and only acrylic acid monomer was used, with other steps being the same.

[0061] Comparative Example 7

[0062] Based on Example 1 with adjustments, different from Example 1, in Comparative Example 7, the ratio of paraffin wax to stearic acid in Step 1 was changed to 8:2 (originally 6.5:3.5).

[0063] Test Example: The high-polymer coal spontaneous combustion inhibitor prepared in the aforementioned Examples 1-4 and Comparative Examples 1-7 was tested as follows.

[0064] Preparation of coal samples: First, lignite with an average particle size of 30 mesh was taken and dried to a constant weight at a temperature of 50°C for standby.

[0065] Preparation of inhibited coal samples: 9 g of the high-polymer coal spontaneous combustion inhibitor was weighed and dissolved in a 30 mL volumetric flask to prepare a dilution solution. Then, 12 mL of the dilution solution was measured and added to 30 g of the dried lignite sample and stirred evenly. It was dried at a temperature of 50°C, and after the coal sample reached a constant weight, it was tested.

[0066] 1. Inhibition performance test:

[0067] The test method for the inhibition performance of the high-polymer coal spontaneous combustion inhibitor is as follows: Weigh 25 g of the coal sample and put it into the sample tube, check the airtightness of the system, and then place it in a programmed temperature rise oven. Dry air is introduced into the sample tube at a flow rate of 100 mL / min; the programmed temperature rise oven is heated at a rate of 2.5°C / min to 100°C, and then samples are taken every 10 min until the total time reaches 150 min; the CO content generated by the coal sample is measured by WT-80-CO produced by Shanghai Yiren Electric Co., Ltd., and the average value of the CO concentration is taken to reflect the inhibition performance of the polymer-based inhibitor.

[0068] Blank control: Weigh 25 g of the dried lignite, and after testing by the same inhibition performance method as above, the measured CO concentration was 122 ppm.

[0069] Control with existing technology: Weigh 25 g of the dried lignite, and after testing by the same inhibition performance method as above, where the inhibitor was changed to the existing commercial inhibitor FR-757, the measured CO concentration was 85 ppm.

[0070] 2. Thermogravimetric experiment

[0071] Instrument: Thermogravimetric Analyzer (TGA, TA Instruments Q50);

[0072] Parameter settings: The usage amount of each inhibited coal sample is 10 mg (±0.01 mg). Under a nitrogen atmosphere, the flow rate is set to 50 mL / min, the heating rate is 10 °C / min, and the heating range is 25 - 700 °C;

[0073] The calculation method of the residual carbon rate is: Residual carbon rate (%) = Remaining mass at 700 °C / Initial sample mass × 100%;

[0074] The test results are shown in Table 1:

[0075] Table 1: Effect test

[0076] CO Concentration (ppm) Initial Decomposition Temperature (°C) Residual Carbon Ratio (700 °C, %) Example 1 46 325 42.5 Example 2 49 320 39.7 Example 3 56 312 38.9 Example 4 53 316 39.4 Comparative Example 1 82 280 28.3 Comparative Example 2 68 305 36.1 Comparative Example 3 61 315 38.9 Comparative Example 4 75 290 31.7 Comparative Example 5 59 312 39.8 Comparative Example 6 72 298 33.6 Comparative Example 7 65 298 34.2

[0077] The above data show that Example 1 (46 ppm) is significantly better than the blank control (122 ppm) and the prior art control (85 ppm), indicating its excellent inhibition effect. In Comparative Example 1, the CO concentration increased to 82 ppm, indicating that the microcapsules delay the exothermic oxidation of coal by encapsulating the paraffin / stearic acid phase change material. In Comparative Example 2, the CO concentration rose to 68 ppm, indicating that the GMA grafting enhanced the interfacial bonding between the CNC and the polymer network, improving the inhibitor coverage efficiency. In Comparative Example 5, the CO concentration of 58 ppm is slightly higher than that of Example 1, indicating that low-temperature freeze-drying forms a more uniform porous structure, enhancing the permeability of the inhibitor. In Comparative Example 6, the CO concentration is 72 ppm, indicating that acrylamide enhances the gel network through hydrogen bonds, improving the stability of the inhibitor.

[0078] In addition, the initial decomposition temperature of Example 1 is the highest and that of Comparative Example 1 is the lowest, indicating that the polydopamine microcapsules and GMA-grafted CNC synergistically improve the thermal stability. In Comparative Example 3, the initial decomposition temperature is 315 °C and the residual carbon rate is 38.9%, indicating that the cross-linking effect of N,N'-methylenebisacrylamide is better than that of ethylene glycol dimethacrylate. In Comparative Example 7, the initial decomposition temperature is 298 °C and the residual carbon rate is 34.2%, indicating that too high a paraffin ratio leads to a decrease in the microcapsule encapsulation efficiency and premature release of the phase change material. And Example 1 is significantly higher than other groups, and Comparative Example 1 is the lowest, further verifying the carbonized skeleton of the polydopamine microcapsules and the strengthening effect of CNC.

[0079] As used in the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different names to refer to the same component. The specification and claims do not distinguish components by the difference in names, but by the difference in their functions. As used throughout the specification and claims, the terms "comprising" and "including" are open-ended terms and should be interpreted as "comprising / including but not limited to". "Substantially" means within an acceptable error range. Those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description in the specification is a preferred embodiment for implementing the present application, but the description is for the purpose of explaining the general principles of the present application and is not intended to limit the scope of the present application. The protection scope of the present application shall be subject to what is defined by the appended claims.

[0080] It should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a commodity or system including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent in such commodity or system. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of another identical element in the commodity or system including the said element.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and not to limit the technical solutions described in the present invention; those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced; and all technical solutions and their improvements that do not depart from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims

1. A preparation process of a polymer coal spontaneous combustion inhibitor, characterized in that, It includes the following steps: S1. Disperse polydopamine microcapsules evenly in deionized water, add GMA-grafted CNC, and stir until uniform to obtain a mixed solution; S2. Sequentially add acrylic acid and acrylamide to the mixed solution prepared in step S1, then add a crosslinking agent and an initiator, stir under nitrogen protection, form a gel after reaction, immerse the gel in ethanol to displace water, and obtain the high-polymer coal spontaneous combustion inhibitor after freeze-drying.

2. The preparation process of a high-polymer coal spontaneous combustion inhibitor according to claim 1, characterized in that, The weight ratio of the polydopamine microcapsules, deionized water, GMA-grafted CNC, acrylic acid, acrylamide, crosslinking agent, and initiator is (3-5):(50-60):(4-5):(14-16):(4-6):(0.5-0.7):(1-1.4).

3. The preparation process of a high-polymer coal spontaneous combustion inhibitor according to claim 1, characterized in that, The preparation method of the polydopamine microcapsules includes the following steps: Mix paraffin and stearic acid, melt and stir to form a homogeneous complex, cool to room temperature, crush into powder for standby; Dissolve the homogeneous complex powder in ethanol, add it to an aqueous solution of sodium dodecyl sulfate, ultrasonically emulsify to form an O / W emulsion, add a dopamine hydrochloride solution to the emulsion, stir, centrifuge, wash, and dry to obtain.

4. The preparation process of a high-polymer coal spontaneous combustion inhibitor according to claim 3, characterized in that, The weight ratio of the paraffin and stearic acid is (6-7):(3-4).

5. The preparation process of a high-polymer coal spontaneous combustion inhibitor according to claim 3, characterized in that, The concentration of the aqueous solution of sodium dodecyl sulfate is 0.5-1 g / 100 mL; the concentration of the dopamine hydrochloride aqueous solution is 2-3 mg / mL; the dosage ratio of the homogeneous complex powder, ethanol, aqueous solution of sodium dodecyl sulfate, and dopamine hydrochloride aqueous solution is (1-2) g:(10-20) mL:(100-110) mL:(85-95) mL.

6. The preparation process of a high-polymer coal spontaneous combustion inhibitor according to claim 1, characterized in that, The preparation method of the GMA-grafted CNC includes the following steps: Disperse cellulose nanocrystals in deionized water, add glycidyl methacrylate, react at 60-70 °C for 6-8 hours, and obtain after centrifugation and washing.

7. The preparation process of a high-polymer coal spontaneous combustion inhibitor according to claim 6, characterized in that, The dosage ratio of the cellulose nanocrystals, deionized water, and glycidyl methacrylate is (5-7) g:(100-110) mL:(2-3) g.

8. The preparation process of a high-polymer coal spontaneous combustion inhibitor according to claim 6, characterized in that, The diameter of the cellulose nanocrystals is 10-20 nm, and the length is 100-300 nm.

9. The preparation process of a polymer coal spontaneous combustion inhibitor according to claim 1, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide; the initiator is ammonium persulfate.

10. The preparation process of a high-polymer coal spontaneous combustion inhibitor according to claim 1, characterized in that, The freeze-drying temperature is -45 to -55 °C, and the time is 24-26 h.