Acid, alkali and heat-resistant aramid rope conveyor belt and preparation method thereof

Abstract

The present application relates to the technical field of conveyor belt preparation, and specifically discloses an acid-, alkali-, and heat-resistant aramid rope conveyor belt and its preparation method. An acid-, alkali-, and heat-resistant aramid rope conveyor belt comprises an aramid cloth core layer, an upper covering rubber layer, and a lower covering rubber layer. The upper covering rubber layer and the lower covering rubber layer are made of the same acid-, alkali-, and heat-resistant rubber composition. The raw materials of the acid-, alkali-, and heat-resistant rubber composition include: EPDM rubber, fluorosilicone rubber, modified silicon carbide, carbon black, acid- and base-responsive microcapsules, zinc oxide, stearic acid, antioxidant, accelerator, and vulcanizer; modified silicon carbide is prepared by growing a mesoporous titanium dioxide layer on the surface of silicon carbide nanowires through atomic layer deposition technology; the wall material of the acid- and base-responsive microcapsules is poly(2-vinylpyridine-co-ethyl acrylate), and the core material is nano-aluminum hydroxide and polydopamine. The conveyor belt of the present application has both excellent heat resistance and acid and alkali corrosion resistance, and can adapt to more complex and harsh material transportation environments.

Description

Technical Field

[0001] The present application relates to the technical field of conveyor belt preparation, and more specifically, to an acid-resistant, alkali-resistant, and heat-resistant aramid rope conveyor belt and a preparation method thereof. Background Art

[0002] Conveyor belts, as a crucial material transport mechanism, are used in numerous industries, including mining, ports, chemicals, and power generation. In real-world environments, conveyor belts often face complex and demanding conditions. In chemical production and mining, acids and alkalis in materials can corrode the belts, reducing their strength and service life. High temperatures are also a common challenge, accelerating the aging of the belt material and potentially causing deformation and breakage, impacting the stable operation of the conveyor system.

[0003] In the related art, for example, the patent document with the announcement number CN103264866B discloses a high-temperature resistant aramid conveyor belt, which includes an aramid fiber cloth and a working surface covering rubber. The working surface covering rubber is coated on the surface of the aramid fiber cloth. The working surface covering rubber is obtained by mixing epoxy resin, diethylenetriamine and cage-type octapolyethylene silsesquioxane to obtain an aramid impregnation liquid; then, EPDM rubber, zinc oxide, stearic acid, antioxidant RD, terpene resin, coumarone resin and accelerator DM are added to the internal mixer to mix. The process involves refining to obtain a mixed liquid; then adding N330 carbon black, N220 carbon black, TCP flame retardant, and chlorinated paraffin to the resulting mixed liquid and mixing; then adding the aramid impregnation liquid and mixing; after the temperature of the mixed liquid drops, adding the vulcanizing agent DCP, accelerator TT, and sulfur and refining; then cooling the lower sheet to obtain a working surface covering adhesive; applying a small amount of the aramid impregnation liquid to the surface of the aramid fiber cloth; then vulcanizing the resulting working surface covering adhesive and the coated aramid fiber, and cooling and forming the resulting high-temperature resistant aramid conveyor belt. In the above scheme, the conveyor belt obtained by completely combining the aramid fiber cloth with the adhesive layer has the advantage of excellent high-temperature resistance.

[0004] Although the above solution achieves the advantage of high-temperature resistance by completely combining aramid fiber cloth with the adhesive layer, it does not mention the issue of corrosion resistance. In actual use, when in complex working conditions such as chemical production and mining where acidic and alkaline substances are present, the adhesive layer and aramid fibers of the conveyor belt are susceptible to acid and alkali corrosion, causing the adhesive layer to swell and the performance of the aramid fibers to deteriorate, seriously affecting the service life and stability of the conveyor belt, making it difficult to meet the comprehensive performance requirements of conveyor belts in special industrial scenarios. Therefore, it is urgent to provide a conveyor belt that is both heat-resistant and acid- and alkali-resistant to adapt to more complex and harsh material transportation environments. Summary of the Invention

[0005] In order to provide a conveyor belt with good heat resistance and acid and alkali corrosion resistance, the present application provides an acid, alkali and heat-resistant aramid rope conveyor belt and a preparation method thereof.

[0006] The present application provides an acid, alkali and heat resistant aramid rope conveyor belt adopting the following technical solutions:

[0007] An acid, alkali and heat-resistant aramid rope conveyor belt comprises an aramid cloth core layer, an upper covering rubber layer and a lower covering rubber layer, wherein the upper covering rubber layer and the lower covering rubber layer are respectively bonded to the upper and lower surfaces of the aramid cloth core layer, and the upper and lower covering rubber layers are made of the same acid, alkali and heat-resistant rubber composition, wherein the acid, alkali and heat-resistant rubber composition comprises the following raw materials in parts by weight:

[0008] 50-70 parts of EPDM rubber, 30-50 parts of fluorosilicone rubber, 10-20 parts of modified silicon carbide, 20-30 parts of carbon black, 5-10 parts of acid-base responsive microcapsules, 3-5 parts of zinc oxide, 1-3 parts of stearic acid, 2-4 parts of antioxidant, 1-3 parts of accelerator and 1-3 parts of vulcanizing agent;

[0009] The modified silicon carbide is prepared by growing a mesoporous titanium dioxide layer on the surface of silicon carbide nanowires through atomic layer deposition technology;

[0010] The wall material of the acid-base responsive microcapsule is poly(2-vinylpyridine-co-ethyl acrylate), and the core material is nano-aluminum hydroxide and polydopamine.

[0011] By adopting this technical solution, EPDM rubber exhibits excellent weather resistance, ozone resistance, and chemical stability, while fluorosilicone rubber offers excellent heat resistance and chemical corrosion resistance. The two are compounded in a specific ratio to significantly enhance the acid, alkali, and heat resistance of the rubber layer while maintaining good elasticity and processing properties. As the rubber matrix, they provide the foundation for the basic physical and mechanical properties and chemical corrosion resistance of the entire rubber composition.

[0012] The modified silicon carbide is made by growing a mesoporous titanium dioxide layer on the surface of silicon carbide nanowires through atomic layer deposition technology. On the one hand, the nanowire structure gives it good dispersibility and thermal conductivity in the rubber matrix, which can effectively improve the heat resistance of the rubber; on the other hand, the mesoporous titanium dioxide layer has high chemical stability and adsorption properties, and can adsorb acid and alkali media, reducing the direct corrosion of acids and alkalis on the rubber, and further improving the acid and alkali resistance of the rubber layer.

[0013] The wall material is poly(2-vinylpyridine-co-ethyl acrylate), which exhibits acid-base responsiveness and undergoes structural changes when exposed to acidic or alkaline substances. The core material is composed of nano-aluminum hydroxide and polydopamine. Nano-aluminum hydroxide neutralizes acids and alkalis, while polydopamine exhibits excellent adhesion and self-healing properties. When the adhesive layer is attacked by acid or alkali, the microcapsule wall material responds to the acidic or alkaline environment and ruptures, releasing the core material. The nano-aluminum hydroxide neutralizes the acid and alkali, while the polydopamine repairs the damaged area. This self-repairs the adhesive layer, effectively resisting acid and alkali attack and extending the service life of the conveyor belt. These raw materials enhance the rubber's hardness, strength, and wear resistance. These additives work synergistically to optimize the overall performance of the rubber composition, ensuring it meets the requirements for acid, alkali, and heat resistance.

[0014] Optionally, the modified silicon carbide is prepared by the following method:

[0015] (1) Add silicon carbide nanowires to a hydrofluoric acid solution, ultrasonically treat for 15-30 minutes at 20-30°C, then filter, take the solid phase and repeatedly rinse with deionized water until neutral, and vacuum dry at 60-80°C for 8-12 hours to complete the surface pretreatment of the silicon carbide nanowires;

[0016] (2) The pretreated silicon carbide nanowires are placed in the reaction chamber of the atomic layer deposition equipment, titanium tetrachloride is used as the titanium source, water is used as the oxygen source, the temperature is set to 150-200 ° C, and the reaction chamber pressure is maintained at 1-5 Pa for atomic layer deposition;

[0017] (3) The product after the reaction in step (2) is taken out from the reaction chamber, placed in a muffle furnace, and calcined at 300-500°C for 2-4 hours to obtain modified silicon carbide.

[0018] By adopting the above technical solution, the silicon carbide nanowires are added to a hydrofluoric acid solution and ultrasonically treated. This removes impurities and oxide layers from the surface of the silicon carbide nanowires, leaving the surface cleaner and rougher. This increases the specific surface area, facilitating the adsorption of titanium and oxygen sources during the subsequent atomic layer deposition process, thereby forming a uniform and dense mesoporous titanium dioxide layer. Precisely controlling temperature and pressure allows for the layer-by-layer growth of high-quality mesoporous titanium dioxide on the surface of the silicon carbide nanowires. This mesoporous structure not only has a large specific surface area, allowing for the absorption of more acidic and alkaline media, but also improves interfacial bonding with the rubber matrix, allowing the modified silicon carbide to be better dispersed in the rubber, thereby achieving both reinforcement and acid and alkali resistance. The resulting product is calcined in a muffle furnace at 300-500°C for 2-4 hours to further optimize the structure of the mesoporous titanium dioxide layer, making it more stable and enhancing its chemical stability and adsorption properties, thereby enhancing the modified silicon carbide's effect on the rubber composition's acid and alkali resistance.

[0019] Optionally, the mass concentration of the hydrofluoric acid solution in step (1) is 5%-10%, and the mass ratio of the silicon carbide nanowires to the hydrofluoric acid solution is 1:(5-7).

[0020] By adopting the above technical solution, the appropriate concentration and mass ratio of hydrofluoric acid solution can ensure the effective removal of impurities and oxide layers on the surface of silicon carbide nanowires while avoiding excessive corrosion of the silicon carbide nanowires, ensuring the structural integrity of the nanowires, thereby ensuring that the subsequent atomic layer deposition process can proceed smoothly, preparing modified silicon carbide with good performance, and ultimately ensuring the acid, alkali and heat resistance of the conveyor belt.

[0021] Optionally, the acid-base responsive microcapsules are prepared by the following method:

[0022] A. 2-vinylpyridine, ethyl acrylate, and azobisisobutyronitrile are mixed, and then stirred under a nitrogen atmosphere for reaction at a temperature of 65-75° C. for 8-12 hours. After the reaction, the reaction liquid is filtered to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then the poly(2-vinylpyridine-co-ethyl acrylate) is dissolved in dimethyl sulfoxide to obtain a wall material solution;

[0023] B. Add nano-aluminum hydroxide and polydopamine to deionized water, and then use an ultrasonic cell crusher for ultrasonic dispersion treatment at an ultrasonic power of 200-300W and an ultrasonic time of 30-60min to obtain a core material dispersion;

[0024] C. Mix the core material dispersion and the wall material solution, add an emulsifier, stir and emulsify for 1-2 hours to form a stable oil-in-water emulsion, distill the oil-in-water emulsion under reduced pressure at 40-50°C for 3-5 hours, and then centrifuge to obtain acid-base responsive microcapsules.

[0025] By adopting the above technical solution and the preparation method, the acid-base responsive microcapsules obtained have an appropriate molecular weight and molecular structure, which gives them good acid-base responsiveness and mechanical strength. In acidic and alkaline environments, they undergo structural changes, causing the microcapsules to rupture and release the core material, nano-aluminum hydroxide, and polydopamine composite repair agent. Nano-aluminum hydroxide can neutralize acids and bases, acting as a buffer; polydopamine has excellent adhesion and chemical stability, and can form a protective film on damaged areas to repair damage to the rubber matrix, thereby enhancing acid and alkali resistance.

[0026] Optionally, the mass ratio of 2-vinylpyridine, ethyl acrylate and azobisisobutyronitrile in step A is (10-15): (8-12): 0.1.

[0027] Optionally, the mass concentration of poly(2-vinylpyridine-co-ethyl acrylate) in the wall material solution in step A is 6%-8%.

[0028] Optionally, in step B, the mass ratio of nano-aluminum hydroxide, polydopamine and deionized water is 1: (0.8-1.2): (10-12).

[0029] Optionally, in step C, the mass ratio of the core material dispersion to the wall material solution is 1:(1.5-2); the emulsifier is Tween-80, and the amount of the emulsifier is 1.5%-2% of the mass of the wall material solution.

[0030] By adopting the above technical solution, the appropriate core material ratio can ensure that the core material has good acid and alkali neutralization and repair properties; the precise emulsification conditions can enable the microcapsules to form a stable structure, ensuring that during the use of the conveyor belt, the microcapsules can rupture and release the core material under the appropriate acid and alkali environment, thereby achieving effective repair of the rubber layer and improving the acid and alkali resistance of the conveyor belt.

[0031] Optionally, the antioxidant is any one of antioxidant 4010NA and antioxidant 4020.

[0032] By adopting the above technical solution, both antioxidants are p-phenylenediamine antioxidants with excellent resistance to heat-oxidative aging, ozone aging, and fatigue aging. During the use of the conveyor belt, they can effectively inhibit the aging reactions of rubber caused by factors such as heat, oxygen, and ozone, preventing the occurrence of aging phenomena such as increased hardness, reduced elasticity, and cracking. This extends the service life of the rubber layer and indirectly improves the acid, alkali, and heat resistance of the conveyor belt. Because aged rubber is more susceptible to acid and alkali corrosion, good anti-aging properties help maintain the rubber's structural stability and enhance its ability to resist acid and alkali.

[0033] The present application also provides a method for preparing an acid-resistant, alkali-resistant and heat-resistant aramid rope conveyor belt, which adopts the following technical solution:

[0034] A method for preparing an acid-resistant, alkali-resistant and heat-resistant aramid rope conveyor belt comprises the following steps:

[0035] S1. Plasticate EPDM rubber and fluorosilicone rubber on an open mill with the roller temperature controlled at 50-60° C. to obtain plasticized rubber;

[0036] S2, adding modified silicon carbide, carbon black, zinc oxide, stearic acid, antioxidant, and accelerator to the plasticized rubber, and mixing in an internal mixer at a mixing temperature of 100-110° C. for 8-10 min. After mixing, adding acid-base responsive microcapsules and a vulcanizing agent, controlling the mixing temperature to 60-80° C., and continuing to mix for 3-5 min. After mixing evenly, the sheet is removed to obtain an acid-, alkali-, and heat-resistant rubber composition;

[0037] S3. Cover the upper and lower surfaces of the aramid cloth core layer with the acid, alkali and heat-resistant rubber composition respectively, add a flat vulcanizing agent, and vulcanize at 160-170° C. and 12-15 MPa pressure for 15-25 minutes to obtain an acid, alkali and heat-resistant aramid rope conveyor belt.

[0038] By adopting the above technical solution and through reasonable process steps and parameter control, it is ensured that the components of the rubber composition are evenly dispersed, and the rubber and the aramid cloth core layer are tightly combined to ensure the overall performance of the conveyor belt.

[0039] In summary, this application has the following beneficial effects:

[0040] 1. This application establishes a solid heat-resistant and acid- and alkali-resistant foundation for conveyor belts through the scientific ratio of EPDM rubber and fluorosilicone rubber. The weather resistance and chemical stability of EPDM rubber complement the excellent heat resistance and chemical corrosion resistance of fluorosilicone rubber, significantly improving the heat and acid- and alkali-resistant capabilities of the rubber layer while ensuring good processing performance and elasticity of the rubber. When the conveyor belt is in a high-temperature environment, the fluorosilicone rubber can stably maintain its structure and performance; when it encounters acid and alkali corrosion, the two work together to effectively block acid and alkali penetration and prevent swelling and degradation of the rubber layer. This allows the conveyor belt to maintain stable conveying performance in complex working conditions such as chemical and mining industries, which are high temperatures and full of acid and alkali challenges, and significantly extends its service life.

[0041] 2. Modified silicon carbide, prepared using atomic layer deposition technology, is uniformly dispersed in the rubber matrix in nanowire form, effectively improving the rubber's thermal conductivity, accelerating heat transfer, preventing local overheating, and enhancing overall heat resistance. Furthermore, the surface-grown mesoporous titanium dioxide layer possesses a strong adsorption capacity, actively capturing acidic and alkaline media, forming a physical barrier that reduces direct contact between the rubber and the acidic and alkaline media, thereby reducing corrosion. Furthermore, the mesoporous structure strengthens the bond with the rubber matrix, stabilizing the dispersion of the modified silicon carbide in the rubber, and making the conveyor belt's heat and acid-base resistance more durable and reliable.

[0042] 3. This application introduces acid-base responsive microcapsules into the raw materials. When the conveyor belt's adhesive layer comes into contact with acidic or alkaline substances, the microcapsule wall material, poly(2-vinylpyridine-co-ethyl acrylate), responds to the acid-base environment, causing structural changes that cause the microcapsules to rupture and release the core materials, nano-aluminum hydroxide and polydopamine. Nano-aluminum hydroxide quickly neutralizes the acid and base, reducing the acid and base concentration in the environment; polydopamine, with its excellent adhesion, forms a tight protective film on damaged areas of the adhesive layer, filling cracks, repairing damage, and actively repairing damage caused by acid and alkaline erosion. This intelligent self-healing mechanism can effectively delay the corrosion of the adhesive layer, greatly improving the conveyor belt's tolerance and service life in acidic and alkaline environments, and ensuring its stable operation under harsh conditions. DETAILED DESCRIPTION

[0043] The present application is further described in detail below with reference to the embodiments.

[0044] Preparation example of modified silicon carbide

[0045] Preparation Example 1

[0046] Modified silicon carbide is prepared by the following method:

[0047] (1) 10 kg of silicon carbide nanowires were added to 50 kg of 5% hydrofluoric acid solution, ultrasonically treated at 20 ° C for 15 min, then filtered, the solid phase was repeatedly rinsed with deionized water until neutral, and vacuum dried at 60 ° C for 8 h to complete the surface pretreatment of the silicon carbide nanowires;

[0048] (2) The pretreated silicon carbide nanowires are placed in the reaction chamber of an atomic layer deposition device, with titanium tetrachloride as the titanium source and water as the oxygen source; titanium tetrachloride gas is first introduced, the reaction chamber pressure is maintained at 1 Pa, the temperature is set to 150 ° C, and the reaction time is 30 s, so that titanium tetrachloride is adsorbed on the surface of the silicon carbide nanowires; then argon gas is introduced for purging, and the purging time is 60 s to remove unreacted titanium tetrachloride; water vapor is then introduced, the pressure is maintained at 5 Pa, the temperature is 200 ° C, and the reaction time is 30 s, so that water vapor reacts with the adsorbed titanium tetrachloride; then argon gas is introduced again for purging for 30 s to remove hydrogen chloride and excess water vapor generated by the reaction; the above process of introducing titanium tetrachloride, purging with inert gas, introducing water vapor, and purging with inert gas is repeated 50 times to grow a mesoporous titanium dioxide layer on the surface of the silicon carbide nanowires;

[0049] (3) The product after the reaction in step (2) is taken out from the reaction chamber, placed in a muffle furnace, and calcined at 300° C. for 4 h to obtain modified silicon carbide.

[0050] Preparation Example 2

[0051] Modified silicon carbide is prepared by the following method:

[0052] (1) 10 kg of silicon carbide nanowires were added to 60 kg of 8% hydrofluoric acid solution, ultrasonically treated at 25 °C for 25 min, then filtered, the solid phase was repeatedly rinsed with deionized water until neutral, and vacuum dried at 70 °C for 10 h to complete the surface pretreatment of the silicon carbide nanowires;

[0053] (2) The pretreated silicon carbide nanowires were placed in the reaction chamber of the atomic layer deposition equipment, with titanium tetrachloride as the titanium source and water as the oxygen source; titanium tetrachloride gas was first introduced, the reaction chamber pressure was maintained at 3Pa, the temperature was set to 180℃, and the reaction time was 30s, so that titanium tetrachloride was adsorbed on the surface of the silicon carbide nanowires; then argon gas was introduced for purging, and the purging time was 60s to remove unreacted titanium tetrachloride; water vapor was introduced again, the pressure was maintained at 5Pa, the temperature was 200℃, and the reaction time was 30s, so that water vapor reacted with the adsorbed titanium tetrachloride; then argon gas was introduced again for purging for 30s to remove hydrogen chloride and excess water vapor generated by the reaction; the above process of introducing titanium tetrachloride, purging with inert gas, introducing water vapor, and purging with inert gas was repeated 50 times to grow a mesoporous titanium dioxide layer on the surface of the silicon carbide nanowires;

[0054] (3) The product after the reaction in step (2) is taken out from the reaction chamber, placed in a muffle furnace, and calcined at 400° C. for 3 h to obtain modified silicon carbide.

[0055] Preparation Example 3

[0056] Modified silicon carbide is prepared by the following method:

[0057] (1) 10 kg of silicon carbide nanowires were added to 70 kg of 10% hydrofluoric acid solution, ultrasonically treated at 30 ° C for 30 min, then filtered, the solid phase was repeatedly rinsed with deionized water until neutral, and vacuum dried at 80 ° C for 12 h to complete the surface pretreatment of the silicon carbide nanowires;

[0058] (2) The pretreated silicon carbide nanowires were placed in the reaction chamber of the atomic layer deposition equipment, with titanium tetrachloride as the titanium source and water as the oxygen source; titanium tetrachloride gas was first introduced, the reaction chamber pressure was maintained at 5 Pa, the temperature was set to 200 ° C, and the reaction time was 30 s, so that titanium tetrachloride was adsorbed on the surface of the silicon carbide nanowires; then argon gas was introduced for purging, and the purging time was 60 s to remove unreacted titanium tetrachloride; water vapor was introduced again, the pressure was maintained at 5 Pa, the temperature was 200 ° C, and the reaction time was 30 s, so that water vapor reacted with the adsorbed titanium tetrachloride; then argon gas was introduced again for purging for 30 s to remove hydrogen chloride and excess water vapor generated by the reaction; the above process of introducing titanium tetrachloride, purging with inert gas, introducing water vapor, and purging with inert gas was repeated 50 times to grow a mesoporous titanium dioxide layer on the surface of the silicon carbide nanowires;

[0059] (3) The product after the reaction in step (2) is taken out from the reaction chamber, placed in a muffle furnace, and calcined at 500° C. for 2 h to obtain modified silicon carbide.

[0060] Preparation Example 4

[0061] The difference between the modified silicon carbide and Preparation Example 3 is that the surface of the silicon carbide nanowires is not pretreated in this Preparation Example.

[0062] Preparation example of acid-base responsive microcapsules

[0063] Preparation Example 5

[0064] Acid-base responsive microcapsules are prepared by the following method:

[0065] A. 10 kg of 2-vinylpyridine, 8 kg of ethyl acrylate, and 0.1 kg of azobisisobutyronitrile were mixed, and then stirred under a nitrogen atmosphere at a reaction temperature of 65° C. for 8 hours. After the reaction, the reaction liquid was filtered to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then dried at 50° C. to constant weight to obtain poly(2-vinylpyridine-co-ethyl acrylate). 10 kg of poly(2-vinylpyridine-co-ethyl acrylate) was dissolved in 156 kg of dimethyl sulfoxide to obtain a wall material solution with a mass concentration of 6% of poly(2-vinylpyridine-co-ethyl acrylate);

[0066] B. Add 10 kg of nano-aluminum hydroxide and 8 kg of polydopamine to 100 kg of deionized water, and then use an ultrasonic cell crusher to perform ultrasonic dispersion treatment at an ultrasonic power of 200 W and an ultrasonic time of 30 min to obtain a core material dispersion;

[0067] C. Mix 10 kg of the core material dispersion with 15 kg of the wall material solution, add 0.225 kg of Tween-80 emulsifier, and stir and emulsify for 1 hour to form a stable oil-in-water emulsion. The oil-in-water emulsion is distilled under reduced pressure at 40° C. for 3 hours, and then centrifuged. The precipitate is collected and washed with deionized water 5 times. The washed microcapsules are dried in a vacuum drying oven at 60° C. for 12 hours to obtain acid-base responsive microcapsules.

[0068] Preparation Example 6

[0069] Acid-base responsive microcapsules are prepared by the following method:

[0070] A. 12 kg of 2-vinylpyridine, 10 kg of ethyl acrylate, and 0.1 kg of azobisisobutyronitrile were mixed, and then stirred under a nitrogen atmosphere at a reaction temperature of 70° C. for 10 hours. After the reaction, the reaction liquid was filtered to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then dried at 50° C. to constant weight to obtain poly(2-vinylpyridine-co-ethyl acrylate). 10 kg of poly(2-vinylpyridine-co-ethyl acrylate) was dissolved in 133 kg of dimethyl sulfoxide to obtain a wall material solution with a mass concentration of 7% of poly(2-vinylpyridine-co-ethyl acrylate);

[0071] B. Add 10 kg of nano-aluminum hydroxide and 10 kg of polydopamine to 110 kg of deionized water, and then use an ultrasonic cell crusher to perform ultrasonic dispersion treatment at an ultrasonic power of 250 W and an ultrasonic time of 50 min to obtain a core material dispersion;

[0072] C. Mix 10 kg of the core material dispersion with 18 kg of the wall material solution, add 0.324 kg of Tween-80 emulsifier, and stir and emulsify for 1.5 hours to form a stable oil-in-water emulsion. Distill the oil-in-water emulsion under reduced pressure at 45°C for 4 hours, then centrifuge and collect the precipitate. Wash the precipitate five times with deionized water, and dry the washed microcapsules in a vacuum drying oven at 60°C for 12 hours to obtain acid-base responsive microcapsules.

[0073] Preparation Example 7

[0074] Acid-base responsive microcapsules are prepared by the following method:

[0075] A. 15 kg of 2-vinylpyridine, 12 kg of ethyl acrylate, and 0.1 kg of azobisisobutyronitrile were mixed, and then stirred under a nitrogen atmosphere at a reaction temperature of 75° C. for 12 hours. After the reaction, the reaction liquid was filtered to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then dried at 50° C. to constant weight to obtain poly(2-vinylpyridine-co-ethyl acrylate). 10 kg of poly(2-vinylpyridine-co-ethyl acrylate) was dissolved in 115 kg of dimethyl sulfoxide to obtain a wall material solution with a mass concentration of 8% of poly(2-vinylpyridine-co-ethyl acrylate);

[0076] B. Add 10 kg of nano-aluminum hydroxide and 12 kg of polydopamine to 120 kg of deionized water, and then use an ultrasonic cell crusher to perform ultrasonic dispersion treatment at an ultrasonic power of 300 W and an ultrasonic time of 60 min to obtain a core material dispersion;

[0077] C. Mix 10 kg of the core material dispersion with 20 kg of the wall material solution, add 0.4 kg of Tween-80 emulsifier, and stir and emulsify for 1.5 hours to form a stable oil-in-water emulsion. Distill the oil-in-water emulsion under reduced pressure at 50° C. for 5 hours, then centrifuge and collect the precipitate. Wash the precipitate five times with deionized water, and dry the washed microcapsules in a vacuum drying oven at 60° C. for 12 hours to obtain acid-base responsive microcapsules.

[0078] Preparation Example 8

[0079] The difference between the acid-base responsive microcapsules and Preparation Example 5 is that the wall material in this Preparation Example is poly(methyl methacrylate-co-butyl acrylate). The specific preparation method of the wall material dispersion is as follows:

[0080] 10 kg of methyl methacrylate, 8 kg of butyl acrylate, and 0.1 kg of potassium persulfate were mixed, and 100 kg of deionized water was added. The mixture was stirred under a nitrogen atmosphere at 75°C for 6 hours to produce a poly(methyl methacrylate-co-butyl acrylate) emulsion. The emulsion was demulsified with acetone and filtered. The solid phase was vacuum-dried at 50°C to constant weight to obtain poly(methyl methacrylate-co-butyl acrylate). 10 kg of poly(methyl methacrylate-co-butyl acrylate) was dissolved in 156 kg of ethyl acetate and stirred at 40°C until completely dissolved, yielding a 6% poly(2-vinylpyridine-co-ethyl acrylate) wall material solution.

[0081] Preparation Example 9

[0082] The difference between the acid-base responsive microcapsules and Preparation Example 5 is that in this Preparation Example, only nano-aluminum hydroxide is used as the core material, polydopamine is not added in step B, and the difference is supplemented by nano-aluminum hydroxide.

[0083] Preparation Example 10

[0084] The difference between the acid-base responsive microcapsules and Preparation Example 5 is that in this Preparation Example, only polydopamine is used as the core material, and no nano-aluminum hydroxide is added in step B, and the difference is supplemented by polydopamine.

[0085] Example

[0086] Example 1

[0087] An acid-, alkali-, and heat-resistant aramid rope conveyor belt comprises an aramid cloth core layer, an upper cover rubber layer, and a lower cover rubber layer, the upper and lower cover rubber layers being bonded to the upper and lower surfaces of the aramid cloth core layer, respectively. The upper and lower cover rubber layers are made from the same acid-, alkali-, and heat-resistant rubber composition. The raw material components and amounts of the acid-, alkali-, and heat-resistant rubber composition are shown in Table 1. The modified silicon carbide is the modified silicon carbide prepared in Preparation Example 1, the acid-, alkali-responsive microcapsules are the acid-, alkali-responsive microcapsules prepared in Preparation Example 5, the antioxidant is 4010NA, the accelerator is dibenzothiazole disulfide, and the vulcanizing agent is dicumyl peroxide.

[0088] A method for preparing an acid-resistant, alkali-resistant and heat-resistant aramid rope conveyor belt comprises the following steps:

[0089] S1. Plasticate EPDM rubber and fluorosilicone rubber on an open mill with the roller temperature controlled at 50° C. to obtain plasticized rubber;

[0090] S2, add modified silicon carbide, carbon black, zinc oxide, stearic acid, antioxidant, accelerator to the plasticized rubber, adopt internal mixer to mix, mixing temperature is 100 ℃, time is 8min, after mixing, add acid-base responsive microcapsules and vulcanizing agent, control mixing temperature is 60 ℃, continue mixing for 3min, mix evenly and then sheet, obtain acid, alkali and heat resistant rubber composition;

[0091] S3. Cover the upper and lower surfaces of the aramid cloth core layer with the acid, alkali and heat-resistant rubber composition respectively, add a flat vulcanizing agent, and vulcanize at 160° C. and 12 MPa pressure for 15 minutes to obtain an acid, alkali and heat-resistant aramid rope conveyor belt.

[0092] Example 2

[0093] A kind of acid, alkali and heat-resistant aramid rope conveyor belt, which is different from Example 1 in that the raw material components and amounts of the acid, alkali and heat-resistant rubber composition are different. The specific amounts are shown in Table 1. Among them, the modified silicon carbide is the modified silicon carbide prepared in Preparation Example 2, the acid-base responsive microcapsules are the acid-base responsive microcapsules prepared in Preparation Example 5, the antioxidant is antioxidant 4020, the accelerator is dibenzothiazole disulfide, and the vulcanizing agent is diisopropylbenzene peroxide.

[0094] A method for preparing an acid-resistant, alkali-resistant and heat-resistant aramid rope conveyor belt comprises the following steps:

[0095] S1. Plasticate EPDM rubber and fluorosilicone rubber on an open mill with the roller temperature controlled at 55° C. to obtain plasticized rubber;

[0096] S2, add modified silicon carbide, carbon black, zinc oxide, stearic acid, antioxidant, accelerator to the plasticized rubber, adopt internal mixer to mix, mixing temperature is 105 ℃, time is 9min, after mixing, add acid-base responsive microcapsules and vulcanizing agent, control mixing temperature to 70 ℃, continue mixing for 4min, mix well and then sheet, obtain acid, alkali and heat resistant rubber composition;

[0097] S3. Cover the upper and lower surfaces of the aramid cloth core layer with the acid, alkali and heat-resistant rubber composition respectively, add a flat vulcanizing agent, and vulcanize at 165° C. and 14 MPa pressure for 20 minutes to obtain an acid, alkali and heat-resistant aramid rope conveyor belt.

[0098] Example 3

[0099] A kind of acid, alkali and heat-resistant aramid rope conveyor belt, which is different from Example 1 in that the raw material components and amounts of the acid, alkali and heat-resistant rubber composition are different. The specific amounts are shown in Table 1. Among them, the modified silicon carbide is the modified silicon carbide prepared in Preparation Example 3, the acid-base responsive microcapsules are the acid-base responsive microcapsules prepared in Preparation Example 5, the antioxidant is antioxidant 4020, the accelerator is dibenzothiazole disulfide, and the vulcanizing agent is diisopropylbenzene peroxide.

[0100] A method for preparing an acid-resistant, alkali-resistant and heat-resistant aramid rope conveyor belt comprises the following steps:

[0101] S1. Plasticate EPDM rubber and fluorosilicone rubber on an open mill with the roller temperature controlled at 60° C. to obtain plasticized rubber;

[0102] S2, add modified silicon carbide, carbon black, zinc oxide, stearic acid, antioxidant, accelerator to the plasticized rubber, adopt internal mixer to mix, mixing temperature is 110 ℃, time is 10min, after mixing, add acid-base responsive microcapsules and vulcanizing agent, control mixing temperature is 80 ℃, continue mixing for 5min, mix evenly and then sheet, obtain acid, alkali and heat resistant rubber composition;

[0103] S3. Cover the upper and lower surfaces of the aramid cloth core layer with the acid, alkali and heat-resistant rubber composition respectively, add a flat vulcanizing agent, and vulcanize at 170° C. and 15 MPa pressure for 25 minutes to obtain an acid, alkali and heat-resistant aramid rope conveyor belt.

[0104] Table 1 Raw material components and amounts of rubber compositions in Examples 1-3 (kg)

[0105]

[0106] Example 4

[0107] An acid-, alkali-, and heat-resistant aramid rope conveyor belt is disclosed. The difference from Example 1 is that the acid-, alkali-, and heat-resistant microcapsules in this embodiment are the acid-, alkali-, and heat-resistant microcapsules prepared in Preparation Example 6.

[0108] Example 5

[0109] An acid-, alkali-, and heat-resistant aramid rope conveyor belt is disclosed. The difference from Example 1 is that the acid-, alkali-, and heat-resistant aramid rope conveyor belt ...

[0110] Example 6

[0111] An acid, alkali and heat-resistant aramid rope conveyor belt is different from Example 1 in that the modified silicon carbide in this example is the modified silicon carbide prepared in Preparation Example 4.

[0112] Comparative Example

[0113] Comparative Example 1

[0114] A high-temperature resistant aramid conveyor belt was prepared according to Example 1 in the patent document with publication number CN103264866B and titled "A High-temperature Resistant Aramid Conveyor Belt".

[0115] Comparative Example 2

[0116] An acid, alkali and heat-resistant aramid rope conveyor belt is different from Example 1 in that an equal amount of untreated silicon carbide is used instead of modified silicon carbide in this comparative example.

[0117] Comparative Example 3

[0118] An acid-, alkali-, and heat-resistant aramid rope conveyor belt is disclosed. The difference from Example 1 is that the acid-, alkali-, and heat-resistant microcapsules in this comparative example are the acid-, alkali-, and heat-resistant microcapsules prepared in Preparation Example 8.

[0119] Comparative Example 4

[0120] An acid-, alkali-, and heat-resistant aramid rope conveyor belt is disclosed. The difference from Example 1 is that the acid-, alkali-, and heat-resistant microcapsules in this comparative example are the acid-, alkali-, and heat-resistant microcapsules prepared in Preparation Example 9.

[0121] Comparative Example 5

[0122] An acid-, alkali-, and heat-resistant aramid rope conveyor belt is disclosed. The difference from Example 1 is that the acid-, alkali-, and heat-resistant microcapsules in this comparative example are the acid-, alkali-, and heat-resistant microcapsules prepared in Preparation Example 10.

[0123] Performance testing

[0124] 1. Heat resistance test

[0125] The heat resistance of the conveyor belts of Examples 1-6 and Comparative Examples 1-5 was tested according to the methods specified in GB / T33510-2017, "Heat Resistance Requirements and Test Methods for Heat-Resistant Rubber-Coated Conveyor Belt Covers." The conveyor belts were classified into three grades: Grade 1: heat resistance up to 100°C; Grade 2: heat resistance up to 125°C; and Grade 3: heat resistance up to 150°C. The test results are shown in Table 2.

[0126] 2. Acid and alkali resistance test

[0127] The conveyor belts of Examples 1-6 and Comparative Examples 1-5 were tested for acid and alkali resistance according to the method specified in HG / T3782-2015, "Acid and Alkali Resistant Conveyor Belts." The acids used were 18% hydrochloric acid and 50% sulfuric acid, and the base was 48% sodium hydroxide. The conveyor belts were immersed in each of the three reagents at 50°C for 96 hours. The post-immersion volume change and strength change rates were calculated, and the average of the three data sets was used. The test results are shown in Table 2.

[0128] Table 2 Test results

[0129]

[0130] It can be seen from Table 2 that the conveyor belts prepared in Examples 1-5 have good heat resistance, and the heat resistance grade is all level 3. The volume expansion rate of the conveyor belts in Examples 1-5 after acid and alkali resistance is between 1.23% and 1.37%, and the strength change rate is between 1.51% and 1.56%. Compared with Comparative Example 1, the volume expansion rate and strength change rate of Examples 1-5 are lower, and therefore have good acid and alkali resistance.

[0131] The volume expansion rate and strength change rate of Example 6 are higher than those of Examples 1-5. Since the modified silicon carbide is not surface pretreated, the performance of the mesoporous titanium dioxide layer is affected, and the adsorption capacity of acid and alkali media and the interfacial bonding force with the rubber matrix are reduced, making the acid and alkali corrosion of the rubber relatively more serious. Therefore, the volume expansion rate and strength change rate are higher than those of other examples.

[0132] In Comparative Example 2, an equal amount of untreated silicon carbide was used in place of the modified silicon carbide. Untreated silicon carbide lacks the high thermal stability and adsorption properties of the mesoporous titanium dioxide layer on the surface of the modified silicon carbide, nor does it effectively improve the thermal conductivity of the rubber as effectively as the modified silicon carbide. Therefore, its heat resistance is inferior to that of the examples, reaching only Grade 2. Untreated silicon carbide cannot absorb acids and bases and enhance its bonding to the rubber matrix like the modified silicon carbide does, and cannot effectively resist acid and alkali corrosion on the rubber. Consequently, its volume expansion rate and strength change rate are higher than those of the examples.

[0133] The wall material of the acid-base responsive microcapsules in Comparative Example 3 is poly(methyl methacrylate-co-butyl acrylate), which does not have the acid-base responsive properties of poly(2-vinylpyridine-co-ethyl acrylate) and cannot effectively release the core material for repair when encountering acidic and alkaline substances. As a result, the rubber matrix is more easily damaged in acidic and alkaline environments, thereby affecting its acid-base resistance.

[0134] Comparative Examples 4 and 5 have relatively high volume expansion rates and strength change rates. In Comparative Example 4, the core material uses only nano-aluminum hydroxide, lacking the adhesion and repair effects of polydopamine; in Comparative Example 5, the core material uses only polydopamine, lacking the acid-base neutralization effect of nano-aluminum hydroxide. In both cases, the repair effect of the microcapsules is inferior to that of the examples containing both nano-aluminum hydroxide and polydopamine. Therefore, in acidic and alkaline environments, the damage to the rubber matrix is relatively large, and the volume expansion rate and strength change rate are relatively high. This shows that the use of nano-aluminum hydroxide and polydopamine as core materials can have a good synergistic effect, thereby jointly improving the acid and alkali resistance of the conveyor belt.

[0135] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An acid, alkali and heat resistant aramid rope conveyor belt, comprising an aramid cloth core layer, an upper cover rubber layer and a lower cover rubber layer, wherein the upper cover rubber layer and the lower cover rubber layer are respectively bonded to the upper and lower surfaces of the aramid cloth core layer, characterized in that: The upper cover rubber layer and the lower cover rubber layer are made of the same acid-resistant, alkali-resistant and heat-resistant rubber composition, and the acid-resistant, alkali-resistant and heat-resistant rubber composition includes the following raw materials in parts by weight: 50-70 parts of EPDM rubber, 30-50 parts of fluorosilicone rubber, 10-20 parts of modified silicon carbide, 20-30 parts of carbon black, 5-10 parts of acid-base responsive microcapsules, 3-5 parts of zinc oxide, 1-3 parts of stearic acid, 2-4 parts of antioxidant, 1-3 parts of accelerator and 1-3 parts of vulcanizing agent; The modified silicon carbide is prepared by the following method: (1) adding silicon carbide nanowires to a hydrofluoric acid solution, ultrasonically treating them at 20-30°C for 15-30 minutes, then filtering, taking the solid phase, repeatedly rinsing with deionized water until neutral, and vacuum drying at 60-80°C for 8-12 hours to complete the surface pretreatment of the silicon carbide nanowires; (2) placing the pretreated silicon carbide nanowires into a reaction chamber of an atomic layer deposition device, using titanium tetrachloride as a titanium source, water as an oxygen source, setting the temperature to 150-200°C, and maintaining the reaction chamber pressure at 1-5 Pa for atomic layer deposition; (3) taking the product after the reaction in step (2) out of the reaction chamber, placing it in a muffle furnace, and calcining it at 300-500°C for 2-4 hours to obtain modified silicon carbide; The acid-base responsive microcapsules are prepared by the following method: A. 2-vinylpyridine, ethyl acrylate and azobisisobutyronitrile are mixed, and then stirred and reacted under a nitrogen atmosphere at a reaction temperature of 65-75° C. for 8-12 hours. After the reaction, the reaction liquid is filtered to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then the poly(2-vinylpyridine-co-ethyl acrylate) is dissolved in dimethyl sulfoxide to obtain a wall material solution; B. Nano-aluminum hydroxide and polydopamine are added to deionized water and ultrasonically dispersed at an ultrasonic power of 200-300 W and for 30-60 minutes to obtain a core material dispersion; C. The core material dispersion is mixed with the wall material solution, an emulsifier is added, and the mixture is stirred and emulsified for 1-2 hours, and then reduced pressure distillation is performed at 40-50° C. for 3-5 hours, and centrifugal separation is performed to obtain the acid-base responsive microcapsules.

2. The acid, alkali and heat resistant aramid rope conveyor belt according to claim 1, characterized in that: The mass concentration of the hydrofluoric acid solution in step (1) is 5%-10%, and the mass ratio of the silicon carbide nanowires to the hydrofluoric acid solution is 1:(5-7).

3. The acid, alkali and heat resistant aramid rope conveyor belt according to claim 1, characterized in that: The mass ratio of 2-vinylpyridine, ethyl acrylate and azobisisobutyronitrile in step A is (10-15): (8-12): 0.

1.

4. The acid, alkali and heat resistant aramid rope conveyor belt according to claim 1, characterized in that: The mass concentration of poly(2-vinylpyridine-co-ethyl acrylate) in the wall material solution in step A is 6%-8%.

5. The acid, alkali and heat resistant aramid rope conveyor belt according to claim 1, characterized in that: In step B, the mass ratio of nano-aluminum hydroxide, polydopamine and deionized water is 1: (0.8-1.2): (10-12).

6. The acid, alkali and heat resistant aramid rope conveyor belt according to claim 1, characterized in that: In step C, the mass ratio of the core material dispersion to the wall material solution is 1:(1.5-2); the emulsifier is Tween-80, and the amount of the emulsifier is 1.5%-2% of the mass of the wall material solution.

7. The acid, alkali and heat resistant aramid rope conveyor belt according to claim 1, characterized in that: The antioxidant is any one of antioxidant 4010NA and antioxidant 4020.

8. A method for preparing the acid-, alkali- and heat-resistant aramid rope conveyor belt according to any one of claims 1 to 7, characterized in that: The steps include: S1. Plasticate EPDM rubber and fluorosilicone rubber on an open mill with the roller temperature controlled at 50-60° C. to obtain plasticized rubber; S2, adding modified silicon carbide, carbon black, zinc oxide, stearic acid, antioxidant, and accelerator to the plasticized rubber, and mixing in an internal mixer at a mixing temperature of 100-110° C. for 8-10 min. After mixing, adding acid-base responsive microcapsules and a vulcanizing agent, controlling the mixing temperature to 60-80° C., and continuing to mix for 3-5 min. After mixing evenly, the sheet is removed to obtain an acid-, alkali-, and heat-resistant rubber composition; S3. Cover the upper and lower surfaces of the aramid cloth core layer with the acid, alkali and heat-resistant rubber composition respectively, add a flat vulcanizing agent, and vulcanize at 160-170° C. and 12-15 MPa pressure for 15-25 minutes to obtain an acid, alkali and heat-resistant aramid rope conveyor belt.

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