Polyurethane material for coal mine plugging and preparation method thereof

Abstract

The application provides a coal mine plugging polyurethane material and a preparation method thereof, and belongs to the technical field of polyurethane. Melamine formaldehyde resin spheres and ZnAl-LDHs are prepared, the two are mixed and reacted to obtain LDH-MF composite spheres, the composite spheres are immersed in an iron salt solution and calcined to obtain composite spheres, the composite spheres are chlorinated by means of dichloro sulfoxide, and the composite spheres are reacted with ionic liquid and hyperbranched polyester to obtain IL / G composite spheres, the IL / G composite spheres are mixed with polyether polyol and a catalyst and added into water, a foaming agent and silicone oil are added, heating and stirring are carried out, the mixture is transferred into a mold, diisocyanate is added, foaming is carried out, the temperature is reduced to room temperature, drying and curing are carried out, and the coal mine plugging polyurethane material is prepared. The coal mine plugging polyurethane material prepared by the application has good mechanical properties, high-temperature resistance and antibacterial property, is good in flexibility and antistatic property, and is obviously improved in flame retardancy, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of polyurethane technology, specifically to a polyurethane material for sealing leaks in coal mines and its preparation method. Background Technology

[0002] Polyurethane (PU) is a high-performance polymer material. Its main raw materials include polyols (such as polyester polyols and polyether polyols), diisocyanates (such as MDI and TDI), and chain extenders and catalysts are added depending on the reaction conditions. It is formed through a polycondensation reaction between polyols and polyisocyanates. Polyurethane materials are mainly classified into polyether type, polyester type, polyimide type, and polyurea type, and are widely used in various fields.

[0003] Wall sealing, as a major measure for preventing gas disasters, has attracted in-depth research from many scholars. By spraying gas sealing materials onto the walls of coal mine roadways, the gas leakage channels on the roadway surface are blocked in a "sealing" manner. Combined with the gas extraction technology inside the coal mine wall, this can not only effectively prevent gas from surging out of the roadway and ensure the safe and efficient operation of underground coal mining, but also increase the gas concentration in the coal seam to facilitate extraction and utilization, thereby significantly increasing coal mine production capacity.

[0004] Chinese invention patent CN104909636B describes a structure comprising "a fast-setting expanding material, microcapsules containing a healing agent, and a catalyst. The fast-setting expanding material includes several of the following: cement clinker, fly ash, steel slag, stone powder, salt mud, carbide slag, expanding agent, water-reducing agent, and sand. The microcapsules consist of a wall material (polymer resin) and a core material (healing agent). It boasts advantages such as automatic detection, automatic healing, moderate expansion, rapid setting, good transportability, strong consolidation, environmental friendliness, and low price." While this patent can achieve a sealing effect, it lacks excellent flame retardant and fire-resistant properties, as well as protection against electric shock. Therefore, its application in coal mines would be unsafe.

[0005] Chinese invention patent CN103388486B describes a material that is produced by reacting and polymerizing 2%-6% polyvinyl alcohol, 1%-5% phosphoric acid, and 1%-5% urea in an aqueous solvent, followed by adding 4%-10% white latex and 2%-6% melamine for further reaction, and then adding 15%-25% inorganic aggregate and mixing thoroughly to obtain the final product. The material has strong wall adhesion and can be easily sprayed onto the surface of coal seams and windbreaks; it has good flame retardant and carbonization properties, forming an expanded carbonized layer thicker than the original uncarbonized layer, and carbonization only occurs at the point of direct contact with the flame during combustion, without flame propagation. It has good workability and can be applied using spraying equipment. However, while the provided air-sealing material has flame-retardant properties, it relies solely on the inherent characteristics of polyvinyl alcohol and ammonium polyphosphate raw materials for flame retardancy, without modifying the inorganic aggregate used. This results in poor flame retardant performance, and it also lacks excellent tensile strength and anti-static properties.

[0006] In conclusion, developing a flame-retardant, antistatic, and mechanically superior coal mine spray sealing material is a critical issue that urgently needs to be addressed in the field of sealing materials technology. Summary of the Invention

[0007] The purpose of this invention is to propose a polyurethane material for sealing leaks in coal mines and its preparation method. It overcomes the problems of traditional materials, has good mechanical properties, high temperature resistance and antibacterial properties, good flexibility, good antistatic properties, and significantly improved flame retardancy, and has broad application prospects.

[0008] The technical solution of this invention is implemented as follows:

[0009] This invention provides a method for preparing polyurethane material for sealing leaks in coal mines. The method involves preparing melamine-formaldehyde resin balls and ZnAl-LDHs, mixing and reacting them to obtain LDH-MF composite balls, impregnating them with an iron salt solution, calcining them to obtain composite balls, chlorinating them with thionyl chloride, reacting them with an ionic liquid and hyperbranched polyester to obtain IL / G composite balls, mixing them with polyether polyol and a catalyst, adding them to water, adding a foaming agent and silicone oil, heating and stirring to mix, transferring the mixture to a mold, adding diisocyanate, foaming, cooling to room temperature, drying, and curing to obtain the polyurethane material for sealing leaks in coal mines.

[0010] As a further improvement to the present invention, the following steps are included:

[0011] S1. Formaldehyde and melamine are added to water, heated and stirred, polyvinyl alcohol and citric acid are added to initiate polymerization, the reaction is kept at a constant temperature and stirred, centrifuged, washed and dried to obtain melamine-formaldehyde resin balls;

[0012] S2. Add zinc salt and aluminum salt to nitric acid solution, add alkaline solution of NaOH and NaNO3 under inert gas protection, heat and stir, adjust the pH value of the solution, microwave heating reaction, centrifuge, wash, dry, and obtain ZnAl-LDHs;

[0013] S3. Add ZnAl-LDHs to water, add melamine-formaldehyde resin balls, ultrasonically disperse evenly, adjust the pH of the solution, stir the reaction, centrifuge, wash, and dry to obtain LDH-MF composite balls;

[0014] S4. Add LDH-MF composite balls to water, add iron salt, soak, centrifuge, wash, dry, and calcine to obtain composite balls;

[0015] S5. Add the composite spheres to dichloromethane, add thionyl chloride, stir to react, centrifuge, wash, and dry to obtain chlorinated composite spheres;

[0016] S6. Trimethylolpropane, trimellitic anhydride and catalyst are added to a solvent, and the reaction is heated and stirred under inert gas protection until the acid value remains unchanged. Glycidyl tert-carbonate is added, and the reaction is heated and stirred until the acid value remains unchanged. The solvent is removed under reduced pressure to obtain hyperbranched polyester.

[0017] S7. Add ionic liquid and hyperbranched polyester to solvent, add alkali and chlorinated composite spheres, heat and stir to react, centrifuge, wash, dry, and obtain IL / G composite spheres;

[0018] S8. Mix polyether polyol, IL / G composite spheres, and catalyst in water, add foaming agent and silicone oil, heat and stir to mix, transfer to mold, add diisocyanate, and after foaming is completed and the material temperature drops to room temperature, dry and heat to cure to obtain polyurethane material for coal mine sealing.

[0019] As a further improvement of the present invention, the mass ratio of formaldehyde, melamine, polyvinyl alcohol and citric acid in step S1 is 1-3:1-3:0.3-0.7:0.1-0.3, the heating and stirring temperature is 75-85℃, and the heat preservation and stirring reaction time is 10-20 min.

[0020] As a further improvement of the present invention, in step S2, the mass ratio of zinc salt, aluminum salt, nitric acid solution, NaOH and NaNO3 alkaline solution is 2-2.6:3-4:150-200:80-100, the concentration of the nitric acid solution is 2-4 wt%, and the alkaline solution of NaOH and NaNO3 is prepared by adding 7-9 g of NaOH and 1-1.5 mL of concentrated nitric acid to 100 mL of water, stirring and dissolving. The pH value of the adjusted solution is 7-9, the microwave heating reaction temperature is 40-50℃, the power is 400-500 W, and the time is 1-2 h. The zinc salt is selected from at least one of zinc chloride, zinc sulfate, and zinc nitrate, and the aluminum salt is aluminum nitrate. In step S3, the mass ratio of ZnAl-LDHs and melamine-formaldehyde resin balls is 2:10-15, the pH value of the adjusted solution is 6-7, and the stirring reaction time is 4-5 h.

[0021] As a further improvement of the present invention, the mass ratio of LDH-MF composite spheres to iron salt in step S4 is 30-50:1-3, the iron salt is selected from at least one of ferric chloride, ferric sulfate, and ferric nitrate, the impregnation time is 10-12h, and the calcination conditions are to raise the temperature to 880-920℃ at a rate of 8-12℃ / min under inert gas protection and hold for 50-70min.

[0022] As a further improvement of the present invention, the mass ratio of the composite ball to thionyl chloride in step S5 is 10:3-5, and the stirring reaction time is 40-50 min.

[0023] As a further improvement of the present invention, the molar ratio of trimethylolpropane, trimellitic anhydride, and glycidyl tert-carbonate in step S6 is 1:3:6-6.6, the amount of catalyst added is 0.02-0.05 wt% of the total mass of trimethylolpropane, the catalyst is triphenylphosphine, the solvent is N,N-dimethylacetamide, the temperature of the heating and stirring reaction is 135-145°C, and the temperature of the heating and stirring reaction is 145-155°C.

[0024] As a further improvement of the present invention, the mass ratio of the ionic liquid, hyperbranched polyester, alkali and chlorinated composite spheres in step S7 is 3-5:2-4:4-7:15-20, the alkali is triethylamine or NaOH, the heating and stirring reaction temperature is 55-65℃, and the time is 2-4h. The ionic liquid is selected from at least one of 1-methylimidazolium chloride, 1-ethylimidazolium chloride, 1-butylimidazolium chloride, 1-pentylimidazolium chloride, 1-hexylimidazolium chloride, 1-methylimidazolium tetrafluoroborate, 1-ethylimidazolium tetrafluoroborate, 1-butylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium hexafluorophosphate.

[0025] As a further improvement of the present invention, the mass ratio of the polyether polyol, IL / G composite spheres, catalyst, foaming agent, silicone oil and diisocyanate in step S8 is 10:2.5-3.5:0.01-0.012:1.2-1.7:1.5-2.5:10-12. The heating and stirring temperature is 50-60℃, the heating and curing temperature is 110-130℃, and the time is 3-5 hours. The polyether polyol is selected from at least one of bisphenol A diethanol ether, polytrimethylene ether glycol, polytetrahydrofuran glycol, tetrahydrofuran-propylene oxide copolymer glycol, and polyoxypropylene glycol. The catalyst is a Raney nickel catalyst. The foaming agent is n-hexane. The diisocyanate is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate, aliphatic isocyanate, naphthalene 1,5-diisocyanate, phenylmethylene diisocyanate, and tetramethyl isophthalimethylene diisocyanate.

[0026] This invention further protects a polyurethane material for sealing leaks in coal mines prepared by the above-described method.

[0027] The present invention has the following beneficial effects:

[0028] This invention prepares melamine-formaldehyde resin microspheres. Using these microspheres as templates, ZnAl-LDHs are encapsulated via electrostatic self-assembly. Iron ions are then loaded using an impregnation method. Through high-temperature calcination, the melamine-formaldehyde resin pyrolyzes to produce CO and NH3, which act as reducing gases, reducing the iron ions to elemental Fe. NH3 also acts as a catalyst, catalyzing the growth of CO (carbon source). This allows for in-situ self-catalytic growth of carbon nanotubes via chemical vapor deposition without the need for hazardous carbon sources or reducing gases. Furthermore, the calcination of ZnAl-LDHs generates alumina and zinc oxide oxides, which, together with the carbonization products on the polymer surface, form a carbon layer, isolating oxygen and heat sources. This method offers advantages such as low cost, good stability, non-toxicity, and environmental friendliness, significantly improving the flame retardancy of the material.

[0029] Meanwhile, the carbon nanotubes generated on its surface also have an intercalation effect. After surface hydroxyl chlorination, chlorinated composite spheres are formed, which react with hyperbranched polyester and ionic liquid to fix the hyperbranched polyester and ionic liquid on the surface of the composite spheres. The addition of ionic liquid endows polyurethane with a high dielectric constant comparable to glass and improves the self-healing rate of polyurethane. At the same time, it inhibits the interaction of hydrogen bonds, resulting in higher tensile strength and elongation at break of polyurethane, and improving flexibility and high-temperature oil resistance.

[0030] In addition, the ionic liquid and carbon nanotube structure improve the antistatic and antibacterial properties of polyurethane, while the remaining hydroxyl groups in the hyperbranched polyester can react with diisocyanate to form a cross-linked polyurethane with higher density, which has better thermal stability and mechanical properties.

[0031] The polyurethane material for sealing leaks in coal mines prepared by this invention has good mechanical properties, high temperature resistance and antibacterial properties, excellent flexibility, good antistatic properties, and significantly improved flame retardancy, and has broad application prospects. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for preparing polyurethane material for sealing leaks in coal mines, including the following steps:

[0035] S1. Add 1g formaldehyde and 1g melamine to 100mL of water, heat to 75℃, stir, add 0.3g polyvinyl alcohol and 0.1g citric acid to initiate polymerization, keep warm and stir for 10min, centrifuge, wash, dry, and obtain melamine formaldehyde resin balls.

[0036] S2. Add 2g zinc chloride and 3g aluminum nitrate to 150g 2wt% nitric acid solution. Under nitrogen protection, add 80g NaOH and NaNO3 alkaline solution, heat to 40℃, stir, adjust the pH of the solution to 7, microwave at 400W and keep warm, stir and react for 1h, centrifuge, wash, dry to obtain ZnAl-LDHs.

[0037] The alkaline solution of NaOH and NaNO3 is prepared by adding 7g NaOH and 1mL of 68wt% concentrated nitric acid to 100mL of water, stirring and dissolving to obtain the alkaline solution of NaOH and NaNO3.

[0038] S3. Add 0.2g ZnAl-LDHs to 200mL of water, add 1g of melamine-formaldehyde resin balls, sonicate at 1000W for 15min, adjust the pH of the solution to 6, stir and react for 4h, centrifuge, wash, dry, and obtain LDH-MF composite balls.

[0039] S4. Add 3g of LDH-MF composite spheres to 100mL of water, add 0.1g of ferric sulfate, soak for 10h, centrifuge, wash, dry, and heat to 880℃ at a rate of 8℃ / min under argon protection, hold for 50min to obtain composite spheres.

[0040] S5. Add 1g of composite spheres to 100mL of dichloromethane, add 0.3g of thionyl chloride, stir and react for 40min, centrifuge, wash, and dry to obtain chlorinated composite spheres;

[0041] S6. Add 0.1 mol of trimethylolpropane, 0.3 mol of trimellitic anhydride and triphenylphosphine to 200 mL of N,N-dimethylacetamide, wherein the amount of triphenylphosphine added is 0.02 wt% of the total mass of trimethylolpropane. Under nitrogen protection, heat to 135 °C and stir the reaction until the acid value remains unchanged. Add 0.6 mol of glycidyl tert-carbonate, raise the temperature to 145 °C and stir the reaction until the acid value remains unchanged. Remove the solvent under reduced pressure to obtain hyperbranched polyester.

[0042] S7. Add 3g of 1-butylimidazolium chloride and 2g of hyperbranched polyester to 200mL of acetonitrile, add 4g of NaOH and 15g of chlorinated composite spheres, heat to 55℃, stir and react for 2h, centrifuge, wash, dry, and obtain IL / G composite spheres.

[0043] S8. Mix 10g of polytetrahydrofuran diol, 2.5g of IL / G composite spheres, and 0.01g of Raney nickel catalyst in 200mL of water, add 1.2g of foaming agent n-hexane and 1.5g of silicone oil, heat to 50℃, stir and mix, transfer to a mold, add 10g of toluene diisocyanate, wait for foaming to complete and the material temperature to drop to room temperature, dry, heat to 110℃, and cure for 3 hours to obtain polyurethane material for coal mine sealing.

[0044] Example 2

[0045] This embodiment provides a method for preparing polyurethane material for sealing leaks in coal mines, including the following steps:

[0046] S1. Add 3g formaldehyde and 3g melamine to 100mL of water, heat to 85℃, stir, add 0.7g polyvinyl alcohol and 0.3g citric acid to initiate polymerization, keep warm and stir for 20min, centrifuge, wash, dry, and obtain melamine formaldehyde resin balls.

[0047] S2. Add 2.6g zinc sulfate and 4g aluminum nitrate to 200g 4wt% nitric acid solution. Under nitrogen protection, add 100g alkaline solution of NaOH and NaNO3, heat to 50℃, stir, adjust the pH of the solution to 9, microwave at 500W and keep warm, stir and react for 2h, centrifuge, wash, dry to obtain ZnAl-LDHs;

[0048] The alkaline solution of NaOH and NaNO3 is prepared by adding 9g NaOH and 1.5mL of 68wt% concentrated nitric acid to 100mL of water, stirring and dissolving to obtain the alkaline solution of NaOH and NaNO3.

[0049] S3. Add 0.2g ZnAl-LDHs to 200mL of water, add 1.5g melamine-formaldehyde resin balls, sonicate at 1000W for 15min, adjust the pH of the solution to 7, stir and react for 5h, centrifuge, wash, and dry to obtain LDH-MF composite balls;

[0050] S4. Add 5g of LDH-MF composite spheres to 100mL of water, add 0.3g of ferric nitrate, soak for 12h, centrifuge, wash, dry, and heat to 920℃ at a rate of 12℃ / min under argon protection, hold for 70min to obtain composite spheres;

[0051] S5. Add 1g of composite spheres to 100mL of dichloromethane, add 0.5g of thionyl chloride, stir and react for 50min, centrifuge, wash, dry, and obtain chlorinated composite spheres;

[0052] S6. 0.1 mol of trimethylolpropane, 0.3 mol of trimellitic anhydride and triphenylphosphine were added to 200 mL of N,N-dimethylacetamide, wherein the amount of triphenylphosphine added was 0.05 wt% of the total mass of trimethylolpropane. Under nitrogen protection, the mixture was heated to 145 °C and stirred until the acid value remained unchanged. Then, 0.66 mol of glycidyl tert-carbonate was added, the temperature was raised to 155 °C, and the mixture was stirred until the acid value remained unchanged. The solvent was removed under reduced pressure to obtain hyperbranched polyester.

[0053] S7. Add 5g of 1-pentylimidazolium chloride and 4g of hyperbranched polyester to 200mL of acetonitrile, add 7g of triethylamine and 20g of chlorinated composite spheres, heat to 65℃, stir and react for 4h, centrifuge, wash, dry, and obtain IL / G composite spheres.

[0054] S8. Mix 10g of polytrimethylene ether glycol, 3.5g of IL / G composite spheres, and 0.012g of Raney nickel catalyst in 200mL of water, add 1.7g of foaming agent n-hexane and 2.5g of silicone oil, heat to 60℃, stir and mix, transfer to a mold, add 12g of phthalimide diisocyanate, and after foaming is complete and the material temperature drops to room temperature, dry, heat to 130℃, and cure for 5 hours to obtain polyurethane material for coal mine sealing.

[0055] Example 3

[0056] This embodiment provides a method for preparing polyurethane material for sealing leaks in coal mines, including the following steps:

[0057] S1. Add 2g formaldehyde and 2g melamine to 100mL of water, heat to 80℃, stir, add 0.5g polyvinyl alcohol and 0.2g citric acid to initiate polymerization, keep warm and stir for 15min, centrifuge, wash, dry, and obtain melamine-formaldehyde resin balls.

[0058] S2. Add 2.4g zinc nitrate and 3.4g aluminum nitrate to 170g 3wt% nitric acid solution. Under nitrogen protection, add 90g NaOH and NaNO3 alkaline solution, heat to 45℃, stir, adjust the pH of the solution to 8, microwave at 450W and keep warm, stir and react for 1.5h, centrifuge, wash, dry to obtain ZnAl-LDHs;

[0059] The alkaline solution of NaOH and NaNO3 is prepared by adding 8g of NaOH and 1.2mL of 68wt% concentrated nitric acid to 100mL of water, stirring and dissolving to obtain the alkaline solution of NaOH and NaNO3.

[0060] S3. Add 0.2g ZnAl-LDHs to 200mL of water, add 1.2g melamine-formaldehyde resin balls, sonicate at 1000W for 15min, adjust the pH of the solution to 6.5, stir and react for 4.5h, centrifuge, wash, and dry to obtain LDH-MF composite balls;

[0061] S4. Add 4g of LDH-MF composite spheres to 100mL of water, add 0.3g of ferric chloride, soak for 11h, centrifuge, wash, dry, and heat to 900℃ at a rate of 10℃ / min under argon protection, hold for 60min to obtain composite spheres.

[0062] S5. Add 1g of composite spheres to 100mL of dichloromethane, add 0.4g of thionyl chloride, stir and react for 45min, centrifuge, wash, dry, and obtain chlorinated composite spheres;

[0063] S6. 0.1 mol of trimethylolpropane, 0.3 mol of trimellitic anhydride and triphenylphosphine were added to 200 mL of N,N-dimethylacetamide, wherein the amount of triphenylphosphine added was 0.03 wt% of the total mass of trimethylolpropane. Under nitrogen protection, the mixture was heated to 140 °C and stirred until the acid value remained unchanged. Then, 0.63 mol of glycidyl tert-carbonate was added, the temperature was raised to 150 °C, and the mixture was stirred until the acid value remained unchanged. The solvent was removed under reduced pressure to obtain a hyperbranched polyester.

[0064] S7. Add 4g of 1-hexylimidazolium chloride and 3g of hyperbranched polyester to 200mL of acetonitrile, add 5.5g of triethylamine and 17g of chlorinated composite spheres, heat to 60℃, stir and react for 3h, centrifuge, wash, dry, and obtain IL / G composite spheres.

[0065] S8. Mix 10g of bisphenol A diethanol ether, 3g of IL / G composite spheres, and 0.011g of Raney nickel catalyst in 200mL of water, add 1.5g of foaming agent n-hexane and 2g of silicone oil, heat to 55℃, stir and mix, transfer to a mold, add 11g of diphenylmethane diisocyanate, and after foaming is completed and the material temperature drops to room temperature, dry, heat to 120℃, and cure for 4 hours to obtain polyurethane material for coal mine sealing.

[0066] Comparative Example 1

[0067] The difference from Example 3 is that step S2 was not performed, and ZnAl-LDHs were replaced with tetraethyl orthosilicate.

[0068] Specifically as follows:

[0069] S1. Add 2g formaldehyde and 2g melamine to 100mL of water, heat to 80℃, stir, add 0.5g polyvinyl alcohol and 0.2g citric acid to initiate polymerization, keep warm and stir for 15min, centrifuge, wash, dry, and obtain melamine-formaldehyde resin balls.

[0070] S2. Add 0.2g of tetraethyl orthosilicate to 200mL of water, add 1.2g of melamine-formaldehyde resin balls, sonicate at 1000W for 15min, adjust the pH of the solution to 6.5, stir and react for 4.5h, centrifuge, wash, and dry to obtain primary composite balls;

[0071] S3. Add 4g of primary composite spheres to 100mL of water, add 0.3g of ferric chloride, soak for 11h, centrifuge, wash, dry, and heat to 900℃ at a rate of 10℃ / min under argon protection, hold for 60min to obtain composite spheres;

[0072] S4. Add 1g of composite spheres to 100mL of dichloromethane, add 0.4g of thionyl chloride, stir and react for 45min, centrifuge, wash, and dry to obtain chlorinated composite spheres;

[0073] S5. 0.1 mol of trimethylolpropane, 0.3 mol of trimellitic anhydride and triphenylphosphine were added to 200 mL of N,N-dimethylacetamide, wherein the amount of triphenylphosphine added was 0.03 wt% of the total mass of trimethylolpropane. Under nitrogen protection, the mixture was heated to 140 °C and stirred until the acid value remained unchanged. Then, 0.63 mol of glycidyl tert-carbonate was added, the temperature was raised to 150 °C, and the mixture was stirred until the acid value remained unchanged. The solvent was removed under reduced pressure to obtain hyperbranched polyester.

[0074] S6. Add 4g of 1-hexylimidazolium chloride and 3g of hyperbranched polyester to 200mL of acetonitrile, add 5.5g of triethylamine and 17g of chlorinated composite spheres, heat to 60℃, stir and react for 3h, centrifuge, wash, dry, and obtain IL / G composite spheres.

[0075] S7. Mix 10g of bisphenol A diethanol ether, 3g of IL / G composite spheres, and 0.011g of Raney nickel catalyst in 200mL of water, add 1.5g of foaming agent n-hexane and 2g of silicone oil, heat to 55℃, stir and mix, transfer to a mold, add 11g of diphenylmethane diisocyanate, and after foaming is completed and the material temperature drops to room temperature, dry, heat to 120℃, and cure for 4 hours to obtain polyurethane material for coal mine sealing.

[0076] Comparative Example 2

[0077] The difference from Example 3 is that step S4 was not performed.

[0078] Specifically as follows:

[0079] S1. Add 2g formaldehyde and 2g melamine to 100mL of water, heat to 80℃, stir, add 0.5g polyvinyl alcohol and 0.2g citric acid to initiate polymerization, keep warm and stir for 15min, centrifuge, wash, dry, and obtain melamine-formaldehyde resin balls.

[0080] S2. Add 2.4g zinc nitrate and 3.4g aluminum nitrate to 170g 3wt% nitric acid solution. Under nitrogen protection, add 90g NaOH and NaNO3 alkaline solution, heat to 45℃, stir, adjust the pH of the solution to 8, microwave at 450W and keep warm, stir and react for 1.5h, centrifuge, wash, dry to obtain ZnAl-LDHs;

[0081] The alkaline solution of NaOH and NaNO3 is prepared by adding 8g of NaOH and 1.2mL of 68wt% concentrated nitric acid to 100mL of water, stirring and dissolving to obtain the alkaline solution of NaOH and NaNO3.

[0082] S3. Add 0.2g ZnAl-LDHs to 200mL of water, add 1.2g melamine-formaldehyde resin balls, sonicate at 1000W for 15min, adjust the pH of the solution to 6.5, stir and react for 4.5h, centrifuge, wash, and dry to obtain LDH-MF composite balls;

[0083] S4. Add 1g of LDH-MF composite spheres to 100mL of dichloromethane, add 0.4g of thionyl chloride, stir and react for 45min, centrifuge, wash, and dry to obtain chlorinated composite spheres;

[0084] S5. 0.1 mol of trimethylolpropane, 0.3 mol of trimellitic anhydride and triphenylphosphine were added to 200 mL of N,N-dimethylacetamide, wherein the amount of triphenylphosphine added was 0.03 wt% of the total mass of trimethylolpropane. Under nitrogen protection, the mixture was heated to 140 °C and stirred until the acid value remained unchanged. Then, 0.63 mol of glycidyl tert-carbonate was added, the temperature was raised to 150 °C, and the mixture was stirred until the acid value remained unchanged. The solvent was removed under reduced pressure to obtain hyperbranched polyester.

[0085] S6. Add 4g of 1-hexylimidazolium chloride and 3g of hyperbranched polyester to 200mL of acetonitrile, add 5.5g of triethylamine and 17g of chlorinated composite spheres, heat to 60℃, stir and react for 3h, centrifuge, wash, dry, and obtain IL / G composite spheres.

[0086] S7. Mix 10g of bisphenol A diethanol ether, 3g of IL / G composite spheres, and 0.011g of Raney nickel catalyst in 200mL of water, add 1.5g of foaming agent n-hexane and 2g of silicone oil, heat to 55℃, stir and mix, transfer to a mold, add 11g of diphenylmethane diisocyanate, and after foaming is completed and the material temperature drops to room temperature, dry, heat to 120℃, and cure for 4 hours to obtain polyurethane material for coal mine sealing.

[0087] Comparative Example 3

[0088] The difference from Example 3 is that 1-hexylimidazolium chloride was not added in step S7.

[0089] Specifically as follows:

[0090] S7. Add 7g of hyperbranched polyester to 200mL of acetonitrile, add 5.5g of triethylamine and 17g of chlorinated composite spheres, heat to 60℃, stir and react for 3h, centrifuge, wash, and dry to obtain G composite spheres.

[0091] Comparative Example 4

[0092] The difference from Example 3 is that hyperbranched polyester was not added in step S7.

[0093] Specifically as follows:

[0094] S7. Add 7g of 1-hexylimidazolium chloride to 200mL of acetonitrile, add 5.5g of triethylamine and 17g of chloride composite spheres, heat to 60℃, stir and react for 3h, centrifuge, wash, dry, and obtain IL composite spheres.

[0095] Comparative Example 5

[0096] The difference from Example 3 is that steps S5, S6, and S7 were not performed.

[0097] Specifically as follows:

[0098] S1. Add 2g formaldehyde and 2g melamine to 100mL of water, heat to 80℃, stir, add 0.5g polyvinyl alcohol and 0.2g citric acid to initiate polymerization, keep warm and stir for 15min, centrifuge, wash, dry, and obtain melamine-formaldehyde resin balls.

[0099] S2. Add 2.4g zinc nitrate and 3.4g aluminum nitrate to 170g 3wt% nitric acid solution. Under nitrogen protection, add 90g NaOH and NaNO3 alkaline solution, heat to 45℃, stir, adjust the pH of the solution to 8, microwave at 450W and keep warm, stir and react for 1.5h, centrifuge, wash, dry to obtain ZnAl-LDHs;

[0100] The alkaline solution of NaOH and NaNO3 is prepared by adding 8g of NaOH and 1.2mL of 68wt% concentrated nitric acid to 100mL of water, stirring and dissolving to obtain the alkaline solution of NaOH and NaNO3.

[0101] S3. Add 0.2g ZnAl-LDHs to 200mL of water, add 1.2g melamine-formaldehyde resin balls, sonicate at 1000W for 15min, adjust the pH of the solution to 6.5, stir and react for 4.5h, centrifuge, wash, and dry to obtain LDH-MF composite balls;

[0102] S4. Add 4g of LDH-MF composite spheres to 100mL of water, add 0.3g of ferric chloride, soak for 11h, centrifuge, wash, dry, and heat to 900℃ at a rate of 10℃ / min under argon protection, hold for 60min to obtain composite spheres.

[0103] S5. Mix 10g of bisphenol A diethanol ether, 3g of composite spheres, and 0.011g of Raney nickel catalyst in 200mL of water, add 1.5g of foaming agent n-hexane and 2g of silicone oil, heat to 55℃, stir and mix, transfer to a mold, add 11g of diphenylmethane diisocyanate, and after foaming is completed and the material temperature drops to room temperature, dry, heat to 120℃, and cure for 4 hours to obtain polyurethane material for coal mine sealing.

[0104] Test Example 1

[0105] The polyurethane materials for sealing leaks in coal mines prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to comprehensive performance tests, and the results are shown in Table 1.

[0106] 1. Limiting Oxygen Index (LOI) Test

[0107] According to the GB / T2406.2-2009 standard, each group of materials was made into a shape with a length, width and thickness of 100mm×6.5mm×2mm, and the samples were tested using an HC-2 oxygen index meter.

[0108] 2. Vertical Burning (UL94) Test

[0109] According to the GB / T2408-2021 standard, each group of materials was made into a shape with dimensions of 100mm×12.7mm×2mm, and the samples were tested using a CZF-3 horizontal and vertical measuring instrument.

[0110] 3. Tensile strength and elongation at break tests

[0111] The tensile strength properties of each group of materials were determined according to the test method in GB / T 9641-1988, with a tensile speed of 5 mm / min.

[0112] 4. Surface resistance test

[0113] The surface resistance of each group of materials was determined according to the surface resistance method in MT / T 113-1995.

[0114] Table 1

[0115]

[0116] As can be seen from the table above, the polyurethane materials for sealing leaks in coal mines prepared in Examples 1-3 of this invention have good comprehensive performance.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a polyurethane material for sealing leaks in coal mines, characterized in that, Includes the following steps: S1. Formaldehyde and melamine are added to water, heated and stirred, polyvinyl alcohol and citric acid are added to initiate polymerization, the reaction is kept at a constant temperature and stirred, centrifuged, washed and dried to obtain melamine-formaldehyde resin balls; S2. Add zinc salt and aluminum salt to nitric acid solution, add alkaline solution of NaOH and NaNO3 under inert gas protection, heat and stir, adjust the pH value of the solution, microwave heating reaction, centrifuge, wash, dry, and obtain ZnAl-LDHs; S3. Add ZnAl-LDHs to water, add melamine-formaldehyde resin balls, ultrasonically disperse evenly, adjust the pH of the solution, stir the reaction, centrifuge, wash, and dry to obtain LDH-MF composite balls; S4. Add LDH-MF composite balls to water, add iron salt, soak, centrifuge, wash, dry, and calcine to obtain composite balls; S5. Add the composite spheres to dichloromethane, add thionyl chloride, stir to react, centrifuge, wash, and dry to obtain chlorinated composite spheres; S6. Trimethylolpropane, trimellitic anhydride and catalyst are added to a solvent, and the reaction is heated and stirred under inert gas protection until the acid value remains unchanged. Glycidyl tert-carbonate is added, and the reaction is heated and stirred until the acid value remains unchanged. The solvent is removed under reduced pressure to obtain hyperbranched polyester. S7. Add ionic liquid and hyperbranched polyester to solvent, add alkali and chlorinated composite spheres, heat and stir to react, centrifuge, wash, dry, and obtain IL / G composite spheres; S8. Mix polyether polyol, IL / G composite spheres, and catalyst in water, add foaming agent and silicone oil, heat and stir to mix, transfer to mold, add diisocyanate, and after foaming is completed and the material temperature drops to room temperature, dry and heat to cure to obtain polyurethane material for coal mine sealing.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of formaldehyde, melamine, polyvinyl alcohol and citric acid is 1-3:1-3:0.3-0.7:0.1-0.3, the heating and stirring temperature is 75-85℃, and the heat preservation and stirring reaction time is 10-20 min.

3. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of zinc salt, aluminum salt, nitric acid solution, NaOH, and NaNO3 alkaline solution is 2-2.6:3-4:150-200:80-100, the concentration of the nitric acid solution is 2-4 wt%, and the NaOH and NaNO3 alkaline solution is prepared by adding 7-9 g of NaOH and 1-1.5 mL of concentrated nitric acid to 100 mL of water, stirring to dissolve, and adjusting the pH of the solution to 7-9. The microwave heating reaction temperature is 40-50℃, the power is 400-500 W, and the time is 1-2 h. The zinc salt is selected from at least one of zinc chloride, zinc sulfate, and zinc nitrate, and the aluminum salt is aluminum nitrate. In step S3, the mass ratio of ZnAl-LDHs and melamine-formaldehyde resin balls is 2:10-15, the pH of the solution is adjusted to 6-7, and the stirring reaction time is 4-5 h.

4. The preparation method according to claim 1, characterized in that, In step S4, the mass ratio of LDH-MF composite spheres to iron salt is 30-50:1-3. The iron salt is selected from at least one of ferric chloride, ferric sulfate, and ferric nitrate. The impregnation time is 10-12 hours. The calcination conditions are: under inert gas protection, the temperature is increased to 880-920℃ at a rate of 8-12℃ / min and held for 50-70 minutes.

5. The preparation method according to claim 1, characterized in that, In step S5, the mass ratio of the composite spheres to thionyl chloride is 10:3-5, and the stirring reaction time is 40-50 min.

6. The preparation method according to claim 1, characterized in that, In step S6, the molar ratio of trimethylolpropane, trimellitic anhydride, and glycidyl tert-carbonate is 1:3:6-6.

6. The amount of catalyst added is 0.02-0.05 wt% of the total mass of trimethylolpropane. The catalyst is triphenylphosphine. The solvent is N,N-dimethylacetamide. The temperature of the heating and stirring reaction is 135-145℃. The temperature of the heating and stirring reaction is 145-155℃.

7. The preparation method according to claim 1, characterized in that, In step S7, the mass ratio of the ionic liquid, hyperbranched polyester, alkali, and chlorinated composite spheres is 3-5:2-4:4-7:15-20. The alkali is triethylamine or NaOH. The heating and stirring reaction temperature is 55-65℃, and the time is 2-4 hours. The ionic liquid is selected from at least one of 1-methylimidazolium chloride, 1-ethylimidazolium chloride, 1-butylimidazolium chloride, 1-pentylimidazolium chloride, 1-hexylimidazolium chloride, 1-methylimidazolium tetrafluoroborate, 1-ethylimidazolium tetrafluoroborate, 1-butylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium hexafluorophosphate.

8. The preparation method according to claim 1, characterized in that, In step S8, the mass ratio of polyether polyol, IL / G composite spheres, catalyst, foaming agent, silicone oil, and diisocyanate is 10:2.5-3.5:0.01-0.012:1.2-1.7:1.5-2.5:10-12. The heating and stirring temperature is 50-60℃, and the heating and curing temperature is 110-130℃ for 3-5 hours. The polyether polyol is selected from at least one of bisphenol A diethanol ether, polytrimethylene ether glycol, polytetrahydrofuran glycol, tetrahydrofuran-propylene oxide copolymer glycol, and polyoxypropylene glycol. The catalyst is a Raney nickel catalyst, the foaming agent is n-hexane, and the diisocyanate is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate, aliphatic isocyanate, naphthalene 1,5-diisocyanate, phenylmethylene diisocyanate, and tetramethyl isophthalimethylene diisocyanate.

9. A polyurethane material for sealing leaks in coal mines, prepared by the method according to any one of claims 1-8.

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