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

Abstract

The invention relates to the technical field of conveying belt preparation, and particularly discloses an acid-base-resistant heat-resistant aramid rope conveying belt and a preparation method thereof. An acid-alkali-resistant heat-resistant aramid rope conveying belt comprises an aramid cloth core layer, an upper covering rubber layer and a lower covering rubber layer, and the upper covering rubber layer and the lower covering rubber layer are made of the same acid-alkali-resistant heat-resistant rubber composition. The acid-alkali-resistant heat-resistant rubber composition is prepared from the following raw materials: ethylene propylene diene monomer, fluorinated silicone rubber, modified silicon carbide, carbon black, acid-alkali response type microcapsules, zinc oxide, stearic acid, an anti-aging agent, an accelerant and a vulcanizing agent, the modified silicon carbide is prepared by growing a mesoporous titanium dioxide layer on the surface of a silicon carbide nanowire through an atomic layer deposition technology; the wall material of the acid-base response type microcapsule is poly (2-vinylpyridine-co-ethyl acrylate), and the core material of the acid-base response type microcapsule is nano aluminum hydroxide and polydopamine. The conveying belt has excellent heat resistance and acid and alkali corrosion resistance, and can adapt to more complex and harsh material conveying environments.

Description

Technical Field

[0001] This application relates to the technical field of conveyor belt preparation. More specifically, it relates to an acid and alkali resistant and heat resistant aramid rope conveyor belt and its preparation method. Background Art

[0002] As an important carrier for material transportation, conveyor belts are applied in many industries such as mines, ports, chemical industries, and power industries. In the actual working environment, conveyor belts often face complex and harsh condition tests. In scenarios such as chemical production and mine exploitation, acid and alkali substances in the materials will corrode the conveyor belts, reducing their strength and service life. At the same time, high temperature environments are also common challenges. High temperatures not only accelerate the aging of conveyor belt materials but may also cause conveyor belts to deform and break, affecting the stable operation of the conveying system.

[0003] In related technologies, a patent document with the publication 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-like octapolyvinylsilsesquioxane to get an aramid impregnating solution. Then, ethylene propylene diene monomer rubber, zinc oxide, stearic acid, antioxidant RD, terpene resin, coumarone resin, and accelerator DM are added to a mixer to knead and obtain a mixed solution. Then, N330 carbon black, N220 carbon black, TCP flame retardant, and chlorinated paraffin are added to the obtained mixed solution and kneaded. After completion, the aramid impregnating solution is added and kneaded. After the temperature of the mixed solution drops, vulcanizing agent DCP, accelerator TT, and sulfur are added and kneaded again. After cooling and sheeting, the working surface covering rubber is obtained. A small amount of aramid impregnating solution is coated on the surface of the aramid fiber cloth. The obtained working surface covering rubber and the coated aramid fiber are sulfurized into one body, and after cooling and forming, a high temperature resistant aramid conveyor belt is obtained. In the above solution, the conveyor belt obtained by completely combining the aramid fiber cloth and the rubber layer has the advantage of good high temperature resistance.

[0004] Although the conveyor belt obtained by completely combining the aramid fiber cloth and the rubber layer in the above solution has the advantage of good high temperature resistance, the problem of corrosion resistance is not mentioned. In the actual use process, when in complex working conditions with acid and alkali substances such as chemical production and mine exploitation, the rubber layer and aramid fibers of the conveyor belt are easily corroded by acid and alkali, resulting in swelling of the rubber layer and a decrease in the performance of aramid fibers, seriously affecting the service life and stability of the conveyor belt, and it is difficult to meet the requirements for the comprehensive performance of conveyor belts in special industrial scenarios. Therefore, there is an urgent need to provide a conveyor belt with both heat resistance and acid and alkali corrosion resistance to adapt to more complex and harsh material transportation environments. Summary of the Invention

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

[0006] The acid and alkali resistant and heat resistant aramid rope conveyor belt provided by the present application adopts the following technical solutions: An acid and alkali resistant and heat resistant aramid rope conveyor belt includes an aramid fabric core layer, an upper cover rubber layer and a lower cover rubber layer. The upper cover rubber layer and the lower cover rubber layer are respectively bonded to the upper and lower surfaces of the aramid fabric core layer. The upper cover rubber layer and the lower cover rubber layer are made of the same acid and alkali resistant and heat resistant rubber composition. The acid and alkali resistant and heat resistant rubber composition includes the following raw materials in parts by weight: 50 - 70 parts of ethylene propylene diene monomer 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 growing a mesoporous titanium dioxide layer on the surface of silicon carbide nanowires through atomic layer deposition technology; The wall material of the acid-base responsive microcapsules is poly(2-vinylpyridine-co-ethyl acrylate), and the core material is nano aluminum hydroxide and polydopamine.

[0007] By adopting the above technical solutions, ethylene propylene diene monomer rubber has good weather resistance, ozone resistance and chemical stability, while fluorosilicone rubber has excellent heat resistance and chemical corrosion resistance. When the two are compounded in a specific proportion, it can significantly improve the acid and alkali resistance and heat resistance of the rubber layer while ensuring good elasticity and processing performance of the rubber. As the rubber matrix, they provide the basic physical and mechanical properties and the basis of chemical corrosion resistance for the whole rubber composition.

[0008] The modified silicon carbide prepared 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 enables it to have 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, which can adsorb acid-base media and reduce the direct erosion of acid-base on the rubber, further improving the acid and alkali resistance of the rubber layer.

[0009] The wall material is poly(2-vinylpyridine-co-ethyl acrylate), which has acid-base response characteristics and undergoes structural changes when encountering acid or base substances; the core material is nano aluminum hydroxide and polydopamine. Nano aluminum hydroxide can neutralize acids and bases, and polydopamine has good adhesion and self-healing properties. When the adhesive layer is eroded by acids and bases, the microcapsule wall material ruptures in response to the acid-base environment, releasing the core material. Nano aluminum hydroxide neutralizes acids and bases, and polydopamine repairs the damaged part, thus realizing the self-healing of the adhesive layer, effectively resisting acid-base erosion, and prolonging the service life of the conveyor belt. Through the above raw material components, the hardness, strength, wear resistance and other properties of the rubber can be improved. These additives act synergistically to jointly optimize the comprehensive properties of the rubber composition, so as to meet the service requirements of acid-base and heat resistance.

[0010] Optionally, the modified silicon carbide is prepared by the following method: (1) Add silicon carbide nanowires to a hydrofluoric acid solution, ultrasonically treat at 20-30 °C for 15-30 min, then filter, take the solid phase and repeatedly rinse with deionized water until neutral, and vacuum dry at 60-80 °C for 8-12 h to complete the surface pretreatment of the silicon carbide nanowires; (2) Put the pretreated silicon carbide nanowires into the reaction chamber of an atomic layer deposition device, use titanium tetrachloride as the titanium source and water as the oxygen source, set the temperature to 150-200 °C, and maintain the reaction chamber pressure at 1-5 Pa for atomic layer deposition; (3) Take out the product after the reaction in step (2) from the reaction chamber, place it in a muffle furnace, and calcine at 300-500 °C for 2-4 h to obtain modified silicon carbide.

[0011] By adopting the above technical solution, adding silicon carbide nanowires to a hydrofluoric acid solution for ultrasonic treatment can remove impurities and oxide layers on the surface of the silicon carbide nanowires, making the surface cleaner and rougher, increasing the specific surface area, and being beneficial to the adsorption of the titanium source and oxygen source during the subsequent atomic layer deposition process, so as to form a uniform and dense mesoporous titanium dioxide layer. Precise control of temperature and pressure can grow a high-quality mesoporous titanium dioxide layer layer by layer on the surface of the silicon carbide nanowires. This mesoporous structure not only has a large specific surface area and can adsorb more acid-base media, but also can improve the interfacial bonding force with the rubber matrix, enabling the modified silicon carbide to be better dispersed in the rubber and playing a dual role of strengthening and acid-base resistance. Calcining the reaction product in a muffle furnace at 300-500 °C for 2-4 h can further optimize the structure of the mesoporous titanium dioxide layer, make it more stable, improve its chemical stability and adsorption performance, thereby enhancing the improvement effect of the modified silicon carbide on the acid-base resistance performance of the rubber composition.

[0012] Optionally, in step (1), the mass concentration of the hydrofluoric acid solution is 5%-10%, and the mass ratio of the silicon carbide nanowires to the hydrofluoric acid solution is 1:(5-7).

[0013] By adopting the above technical solution, appropriate concentrations and mass ratios of hydrofluoric acid solutions can, while ensuring the effective removal of impurities and oxide layers on the surface of silicon carbide nanowires, avoid over-corroding the silicon carbide nanowires, ensure the structural integrity of the nanowires, thereby ensuring the smooth progress of the subsequent atomic layer deposition process, preparing modified silicon carbide with good performance, and ultimately guaranteeing the acid and alkali resistance and heat resistance of the conveyor belt.

[0014] Optionally, the acid-base responsive microcapsules are prepared by the following method: A. Mix 2-vinylpyridine, ethyl acrylate and azobisisobutyronitrile, and then carry out a stirring reaction under a nitrogen atmosphere. The reaction temperature is 65 - 75 °C, and the reaction time is 8 - 12 h. After the reaction ends, filter the reaction solution to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then dissolve poly(2-vinylpyridine-co-ethyl acrylate) in dimethyl sulfoxide to obtain a wall material solution; B. Add nano-aluminum hydroxide and polydopamine to deionized water, and then perform ultrasonic dispersion treatment with an ultrasonic cell disruptor. The ultrasonic power is 200 - 300 W, and the ultrasonic time is 30 - 60 min to obtain a core material dispersion; C. Mix the core material dispersion with the wall material solution, add an emulsifier, and stir and emulsify for 1 - 2 h to form a stable oil-in-water emulsion. Distill the oil-in-water emulsion under reduced pressure at 40 - 50 °C for 3 - 5 h, and then perform centrifugal separation to obtain the acid-base responsive microcapsules.

[0015] By adopting the above technical solution, the acid-base responsive microcapsules obtained by the above preparation method have appropriate molecular weights and molecular structures, endowing them with good acid-base responsiveness and mechanical strength. They will undergo structural changes in an acid-base environment, causing the microcapsules to rupture and release the core material, the composite repair agent of nano-aluminum hydroxide and polydopamine. Nano-aluminum hydroxide can neutralize acids and alkalis and play a buffering role; polydopamine has excellent adhesion properties and chemical stability, and can form a protective film at the damaged part to repair the damage of the rubber matrix, thereby enhancing the acid and alkali resistance.

[0016] Optionally, the mass ratio of 2-vinylpyridine, ethyl acrylate and azobisisobutyronitrile in step A is (10 - 15):(8 - 12):0.1.

[0017] Optionally, the mass concentration of poly(2-vinylpyridine-co-ethyl acrylate) in the wall material solution in step A is 6% - 8%.

[0018] Optionally, the mass ratio of nano-aluminum hydroxide, polydopamine and deionized water in step B is 1:(0.8 - 1.2):(10 - 12).

[0019] Optionally, the mass ratio of the core material dispersion to the wall material solution in step C is 1:(1.5 - 2); the emulsifier is Tween-80, and the dosage of the emulsifier is 1.5% - 2% of the mass of the wall material solution.

[0020] By adopting the above technical solution, a suitable core material ratio can ensure that the core material has good acid-base neutralization and repair performance; 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 in a suitable acid-base environment, achieving effective repair of the rubber layer and improving the acid and alkali resistance of the conveyor belt.

[0021] Optionally, the anti-aging agent is any one of anti-aging agent 4010NA and anti-aging agent 4020.

[0022] By adopting the above technical solution, these two anti-aging agents are both p-phenylenediamine anti-aging agents and have excellent anti-thermal oxygen aging, anti-ozone aging, and anti-fatigue aging properties. During the use of the conveyor belt, they can effectively inhibit the aging reaction of rubber caused by factors such as heat, oxygen, and ozone, prevent the occurrence of aging phenomena such as increased rubber hardness, decreased elasticity, and cracking, thereby extending the service life of the rubber layer and indirectly enhancing the acid and alkali resistance and heat resistance of the conveyor belt. Because aged rubber is more vulnerable to acid and alkali erosion, good anti-aging performance helps to maintain the structural stability of rubber and enhance its ability to resist acids and alkalis.

[0023] The present application also provides a preparation method of an acid and alkali resistant and heat resistant aramid rope conveyor belt, adopting the following technical solution: A preparation method of an acid and alkali resistant and heat resistant aramid rope conveyor belt, comprising the following steps: S1. Plasticate ethylene propylene diene monomer (EPDM) rubber and fluorosilicone rubber on an open mill, controlling the roll temperature at 50 - 60 °C to obtain plasticated rubber; S2. Add modified silicon carbide, carbon black, zinc oxide, stearic acid, anti-aging agent, and accelerator to the plasticated rubber, and mix them using a Banbury mixer at a mixing temperature of 100 - 110 °C for 8 - 10 min. After mixing is completed, add acid-base responsive microcapsules and vulcanizing agent, control the mixing temperature at 60 - 80 °C, and continue to mix for 3 - 5 min. After mixing evenly, take off the sheet to obtain an acid and alkali resistant and heat resistant rubber composition; S3. Cover the acid and alkali resistant and heat resistant rubber composition on the upper and lower surfaces of the aramid fabric core layer respectively, send it into a flat vulcanizer, and vulcanize it at 160 - 170 °C and a pressure of 12 - 15 MPa for 15 - 25 min to prepare an acid and alkali resistant and heat resistant aramid rope conveyor belt.

[0024] By adopting the above technical solution, through reasonable process steps and parameter control, it is ensured that the components of the rubber composition are evenly dispersed, and the rubber is tightly combined with the aramid fabric core layer, guaranteeing the overall performance of the conveyor belt.

[0025] In summary, this application has the following beneficial effects: 1. This application builds a solid heat-resistant and acid-resistant foundation for the conveyor belt 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, which greatly improves the heat and acid resistance of the rubber layer while ensuring the 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 corrosion by acid and alkali substances, the two work together to effectively block the penetration of acid and alkali, avoid swelling and degradation of the rubber layer, and enable the conveyor belt to maintain stable conveying performance under complex working conditions such as chemical and mining industries with high temperatures and full of acid and alkali challenges, and significantly extend its service life.

[0026] 2. Modified silicon carbide prepared by atomic layer deposition technology, on the one hand, the modified silicon carbide in the form of nanowires is evenly dispersed in the rubber matrix, effectively improving the thermal conductivity of the rubber, accelerating heat conduction, preventing local overheating, and improving the overall heat resistance; on the other hand, the mesoporous titanium dioxide layer grown on the surface has a strong adsorption capacity, can actively capture acid and alkali media, form a physical barrier, reduce the direct contact between acid and alkali and rubber, and reduce the degree of corrosion. At the same time, the mesoporous structure can also enhance the bonding force with the rubber matrix, stabilize the dispersion state of modified silicon carbide in the rubber, and make the heat and acid and alkali resistance of the conveyor belt more durable and reliable.

[0027] 3. This application introduces acid-base responsive microcapsules into the raw materials. When the conveyor belt adhesive layer comes into contact with acid and base substances, the microcapsule wall material poly (2-vinylpyridine-co-ethyl acrylate) will respond to the acid-base environment, and the structure will change, causing the microcapsules to rupture and release the core materials nano aluminum hydroxide and polydopamine. Nano aluminum hydroxide quickly reacts with acids and bases to neutralize, reducing the acid and base concentrations in the environment; polydopamine, with its excellent adhesion, forms a tight protective film on the damaged part of the adhesive layer, filling cracks, repairing damage, and actively repairing damage caused by acid and alkali erosion. This intelligent self-repair mechanism can effectively delay the corrosion process of the adhesive layer, greatly improve the tolerance and service life of the conveyor belt in acid and alkali environments, and ensure its stable operation under harsh conditions. DETAILED DESCRIPTION

[0028] The present application is further described in detail below in conjunction with embodiments.

[0029] Preparation example of modified silicon carbide Preparation Example 1 Modified silicon carbide is prepared by the following method: (1) Add 10 kg of silicon carbide nanowires to 50 kg of hydrofluoric acid solution with a mass concentration of 5%, ultrasonically treat for 15 min at 20 °C, then filter, take the solid phase and repeatedly rinse it with deionized water until neutral, and vacuum dry at 60 °C for 8 h to complete the surface pretreatment of the silicon carbide nanowires; (2) Put the pretreated silicon carbide nanowires into the reaction chamber of an atomic layer deposition equipment, use titanium tetrachloride as the titanium source and water as the oxygen source; first introduce titanium tetrachloride gas, maintain the reaction chamber pressure at 1 Pa, set the temperature at 150 °C, and the reaction time at 30 s to adsorb titanium tetrachloride on the surface of the silicon carbide nanowires; then introduce argon for purging, with a purging time of 60 s, to remove the unreacted titanium tetrachloride; then introduce water vapor, maintain the pressure at 5 Pa, the temperature at 200 °C, and the reaction time at 30 s to react the water vapor with the adsorbed titanium tetrachloride; subsequently introduce argon for purging again for 30 s to remove the generated hydrogen chloride and excess water vapor; repeat the process of introducing titanium tetrachloride, inert gas purging, introducing water vapor, and inert gas purging 50 times to grow a mesoporous titanium dioxide layer on the surface of the silicon carbide nanowires; (3) Take out the product after the reaction in step (2) from the reaction chamber, place it in a muffle furnace, and calcine at 300 °C for 4 h to obtain modified silicon carbide.

[0030] Preparation Example 2 Modified silicon carbide is prepared by the following method: (1) Add 10 kg of silicon carbide nanowires to 60 kg of hydrofluoric acid solution with a mass concentration of 8%, ultrasonically treat for 25 min at 25 °C, then filter, take the solid phase and repeatedly rinse it with deionized water until neutral, and vacuum dry at 70 °C for 10 h to complete the surface pretreatment of the silicon carbide nanowires; (2) Put the pretreated silicon carbide nanowires into the reaction chamber of an atomic layer deposition equipment, use titanium tetrachloride as the titanium source and water as the oxygen source; first introduce titanium tetrachloride gas, maintain the reaction chamber pressure at 3 Pa, set the temperature at 180 °C, and the reaction time at 30 s to adsorb titanium tetrachloride on the surface of the silicon carbide nanowires; then introduce argon for purging, with a purging time of 60 s, to remove the unreacted titanium tetrachloride; then introduce water vapor, maintain the pressure at 5 Pa, the temperature at 200 °C, and the reaction time at 30 s to react the water vapor with the adsorbed titanium tetrachloride; subsequently introduce argon for purging again for 30 s to remove the generated hydrogen chloride and excess water vapor; repeat the process of introducing titanium tetrachloride, inert gas purging, introducing water vapor, and inert gas purging 50 times to grow a mesoporous titanium dioxide layer on the surface of the silicon carbide nanowires; (3) Take out the product after the reaction in step (2) from the reaction chamber, place it in a muffle furnace, and calcine at 400 °C for 3 h to obtain modified silicon carbide.

[0031] Preparation Example 3 Modified silicon carbide is prepared by the following method: (1) Add 10 kg of silicon carbide nanowires to 70 kg of hydrofluoric acid solution with a mass concentration of 10%, perform ultrasonic treatment at 30 °C for 30 min, then filter, take the solid phase, repeatedly rinse it with deionized water until neutral, and vacuum dry it at 80 °C for 12 h to complete the surface pretreatment of the silicon carbide nanowires; (2) Put the pretreated silicon carbide nanowires into the reaction chamber of an atomic layer deposition device, use titanium tetrachloride as the titanium source and water as the oxygen source; first introduce titanium tetrachloride gas, maintain the reaction chamber pressure at 5 Pa, set the temperature at 200 °C, and the reaction time at 30 s to adsorb titanium tetrachloride on the surface of the silicon carbide nanowires; then introduce argon for purging, with a purging time of 60 s, to remove unreacted titanium tetrachloride; then introduce water vapor, maintain the pressure at 5 Pa, the temperature at 200 °C, and the reaction time at 30 s to react the water vapor with the adsorbed titanium tetrachloride; subsequently, introduce argon for purging again for 30 s to remove the generated hydrogen chloride and excess water vapor; repeat the process of introducing titanium tetrachloride, inert gas purging, introducing water vapor, and inert gas purging 50 times to grow a mesoporous titanium dioxide layer on the surface of the silicon carbide nanowires; (3) Take out the product after the reaction in step (2) from the reaction chamber, place it in a muffle furnace, and calcine it at 500 °C for 2 h to obtain modified silicon carbide.

[0032] Preparation Example 4 The modified silicon carbide is different from Preparation Example 3 in that the silicon carbide nanowires are not subjected to surface pretreatment in this preparation example.

[0033] Preparation Example of Acid-Base Responsive Microcapsules Preparation Example 5 The acid-base responsive microcapsules are prepared by the following method: A. Mix 10 kg of 2-vinylpyridine, 8 kg of ethyl acrylate, and 0.1 kg of azobisisobutyronitrile, then carry out a stirring reaction under a nitrogen atmosphere, with a reaction temperature of 65 °C and a reaction time of 8 h. After the reaction, filter the reaction solution to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then dry it at 50 °C to constant weight to obtain poly(2-vinylpyridine-co-ethyl acrylate). Take 10 kg of poly(2-vinylpyridine-co-ethyl acrylate) and dissolve it 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); B. Add 10 kg of nano-aluminum hydroxide and 8 kg of polydopamine to 100 kg of deionized water, and then perform ultrasonic dispersion treatment with an ultrasonic cell crusher, with an ultrasonic power of 200 W and an ultrasonic time of 30 min to obtain a core material dispersion liquid; 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, stir and emulsify for 1 h to form a stable oil-in-water emulsion. Distill the oil-in-water emulsion under reduced pressure at 40 °C for 3 h, then perform centrifugal separation, collect the precipitate and wash the precipitate 5 times with deionized water. Dry the washed microcapsules in a vacuum drying oven at 60 °C for 12 h to obtain the acid-base responsive microcapsules.

[0034] Preparation Example 6 The acid-base responsive microcapsules are prepared by the following method: A. Mix 12 kg of 2-vinylpyridine, 10 kg of ethyl acrylate and 0.1 kg of azobisisobutyronitrile, then carry out a stirring reaction under a nitrogen atmosphere. The reaction temperature is 70 °C and the reaction time is 10 h. After the reaction is completed, filter the reaction solution to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then dry it to constant weight at 50 °C to obtain poly(2-vinylpyridine-co-ethyl acrylate). Take 10 kg of poly(2-vinylpyridine-co-ethyl acrylate) and dissolve it 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); B. Add 10 kg of nano-aluminum hydroxide and 10 kg of polydopamine to 110 kg of deionized water, and then perform ultrasonic dispersion treatment with an ultrasonic cell crusher. The ultrasonic power is 250 W and the ultrasonic time is 50 min to obtain the core material dispersion; 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, stir and emulsify for 1.5 h to form a stable oil-in-water emulsion. Distill the oil-in-water emulsion under reduced pressure at 45 °C for 4 h, then perform centrifugal separation, collect the precipitate and wash the precipitate 5 times with deionized water. Dry the washed microcapsules in a vacuum drying oven at 60 °C for 12 h to obtain the acid-base responsive microcapsules.

[0035] Preparation Example 7 The acid-base responsive microcapsules are prepared by the following method: A. Mix 15 kg of 2-vinylpyridine, 12 kg of ethyl acrylate and 0.1 kg of azobisisobutyronitrile, then carry out a stirring reaction under a nitrogen atmosphere. The reaction temperature is 75 °C and the reaction time is 12 h. After the reaction is completed, filter the reaction solution to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then dry it to constant weight at 50 °C to obtain poly(2-vinylpyridine-co-ethyl acrylate). Take 10 kg of poly(2-vinylpyridine-co-ethyl acrylate) and dissolve it 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); B. Add 10 kg of nano aluminum hydroxide and 12 kg of polydopamine into 120 kg of deionized water, and then perform ultrasonic dispersion treatment with an ultrasonic cell disruptor. The ultrasonic power is 300 W and the ultrasonic time is 60 min to obtain the core material dispersion liquid; C. Mix 10 kg of the core material dispersion liquid with 20 kg of the wall material solution, add 0.4 kg of Tween-80 emulsifier, stir and emulsify for 1.5 h to form a stable oil-in-water emulsion. Distill the oil-in-water emulsion under reduced pressure at 50 °C for 5 h, then perform centrifugal separation, collect the precipitate and wash the precipitate 5 times with deionized water. Dry the washed microcapsules in a vacuum drying oven at 60 °C for 12 h to obtain the acid-base responsive microcapsules.

[0036] Preparation Example 8 The acid-base responsive microcapsules are different from those in Preparation Example 5 in that in this preparation example, the wall material is poly(methyl methacrylate-co-butyl acrylate). Specifically, the preparation method of the wall material dispersion liquid is as follows: Mix 10 kg of methyl methacrylate, 8 kg of butyl acrylate and 0.1 kg of potassium persulfate, add 100 kg of deionized water, and carry out a stirring reaction under a nitrogen atmosphere. The reaction temperature is 75 °C and the reaction time is 6 h. After the reaction, a poly(methyl methacrylate-co-butyl acrylate) emulsion is obtained. Demulsify the emulsion with acetone, then filter, and take the solid phase and dry it to constant weight under vacuum at 50 °C to obtain poly(methyl methacrylate-co-butyl acrylate). Take 10 kg of poly(methyl methacrylate-co-butyl acrylate) and dissolve it in 156 kg of ethyl acetate, and stir at 40 °C until completely dissolved to obtain a wall material solution with a mass concentration of 6% of poly(2-vinylpyridine-co-ethyl acrylate).

[0037] Preparation Example 9 The acid-base responsive microcapsules are different from those in Preparation Example 5 in that in this preparation example, the core material only uses nano aluminum hydroxide, and polydopamine is not added in step B, and the difference is made up with nano aluminum hydroxide.

[0038] Preparation Example 10 The acid-base responsive microcapsules are different from those in Preparation Example 5 in that in this preparation example, the core material only uses polydopamine, and nano aluminum hydroxide is not added in step B, and the difference is made up with polydopamine.

[0039] Examples Example 1 An acid and alkali resistant and heat resistant aramid rope conveyor belt, comprising an aramid fabric core layer, an upper cover rubber layer and a lower cover rubber layer. The upper cover rubber layer and the lower cover rubber layer are respectively adhered to the upper and lower surfaces of the aramid fabric core layer, and the upper cover rubber layer and the lower cover rubber layer are made of the same acid and alkali resistant and heat resistant rubber composition. The raw material components and dosages of the acid and alkali resistant and heat resistant rubber composition are shown in Table 1, wherein the modified silicon carbide is the modified silicon carbide prepared in Preparation Example 1, the acid-base responsive microcapsule is the acid-base responsive microcapsule prepared in Preparation Example 5, the anti-aging agent is anti-aging agent 4010NA, the accelerator is dibenzothiazole disulfide, and the vulcanizing agent is dicumyl peroxide.

[0040] A preparation method of an acid and alkali resistant and heat resistant aramid rope conveyor belt, comprising the following steps: S1. Plasticize ethylene propylene diene monomer rubber and fluorosilicone rubber on an open mill, and control the roll temperature at 50 °C to obtain plasticized rubber. S2. Add modified silicon carbide, carbon black, zinc oxide, stearic acid, anti-aging agent, and accelerator to the plasticized rubber, and mix them with a Banbury mixer at a mixing temperature of 100 °C for 8 minutes. After mixing, add the acid-base responsive microcapsule and the vulcanizing agent, control the mixing temperature at 60 °C, and continue mixing for 3 minutes. After mixing evenly, take off the sheet to obtain the acid and alkali resistant and heat resistant rubber composition. S3. Cover the acid and alkali resistant and heat resistant rubber composition on the upper and lower surfaces of the aramid fabric core layer respectively, send it into a flat vulcanizer, and vulcanize it at 160 °C and a pressure of 12 MPa for 15 minutes to obtain the acid and alkali resistant and heat resistant aramid rope conveyor belt.

[0041] Example 2 An acid and alkali resistant and heat resistant aramid rope conveyor belt, which is different from that in Example 1 in that the raw material components and dosages of the acid and alkali resistant and heat resistant rubber composition are different. The specific dosages 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 microcapsule is the acid-base responsive microcapsule prepared in Preparation Example 5, the anti-aging agent is anti-aging agent 4020, the accelerator is dibenzothiazole disulfide, and the vulcanizing agent is dicumyl peroxide.

[0042] A preparation method of an acid and alkali resistant and heat resistant aramid rope conveyor belt, comprising the following steps: S1. Plasticize ethylene propylene diene monomer rubber and fluorosilicone rubber on an open mill, and control the roll temperature at 55 °C to obtain plasticized rubber. S2. Add modified silicon carbide, carbon black, zinc oxide, stearic acid, anti-aging agent, and accelerator to the plasticized rubber, and mix them with a Banbury mixer at a mixing temperature of 105 °C for 9 minutes. After mixing, add the acid-base responsive microcapsule and the vulcanizing agent, control the mixing temperature at 70 °C, and continue mixing for 4 minutes. After mixing evenly, take off the sheet to obtain the acid and alkali resistant and heat resistant rubber composition. S3. Cover the acid- and alkali-resistant and heat-resistant rubber composition on the upper and lower surfaces of the aramid fabric core layer respectively, feed it into a flat vulcanizer, and vulcanize it at 165 °C and a pressure of 14 MPa for 20 minutes to obtain an acid- and alkali-resistant and heat-resistant aramid rope conveyor belt.

[0043] Example 3 An acid- and alkali-resistant and heat-resistant aramid rope conveyor belt, which is different from that in Example 1 in that the raw material components and dosages of the acid- and alkali-resistant and heat-resistant rubber composition are different. The specific dosages 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 microcapsule is the acid-base responsive microcapsule prepared in Preparation Example 5, the antioxidant is antioxidant 4020, the accelerator is dibenzothiazole disulfide, and the vulcanizing agent is dicumyl peroxide.

[0044] A preparation method of an acid- and alkali-resistant and heat-resistant aramid rope conveyor belt includes the following steps: S1. Plasticate ethylene propylene diene monomer (EPDM) rubber and fluorosilicone rubber on an open mill, and control the roll temperature at 60 °C to obtain a plasticated rubber. S2. Add modified silicon carbide, carbon black, zinc oxide, stearic acid, antioxidant, and accelerator to the plasticated rubber, and mix them with a Banbury mixer at a mixing temperature of 110 °C for 10 minutes. After the mixing is completed, add the acid-base responsive microcapsule and the vulcanizing agent, control the mixing temperature at 80 °C, and continue to mix for 5 minutes. After mixing evenly, take off the sheet to obtain an acid- and alkali-resistant and heat-resistant rubber composition. S3. Cover the acid- and alkali-resistant and heat-resistant rubber composition on the upper and lower surfaces of the aramid fabric core layer respectively, feed it into a flat vulcanizer, and vulcanize it at 170 °C and a pressure of 15 MPa for 25 minutes to obtain an acid- and alkali-resistant and heat-resistant aramid rope conveyor belt.

[0045] Table 1 Raw material components and dosages (kg) of the rubber composition in Examples 1-3

[0046] Example 4 An acid- and alkali-resistant and heat-resistant aramid rope conveyor belt, which is different from that in Example 1 in that the acid-base responsive microcapsule in this example is the acid-base responsive microcapsule prepared in Preparation Example 6.

[0047] Example 5 An acid- and alkali-resistant and heat-resistant aramid rope conveyor belt, which is different from that in Example 1 in that the acid-base responsive microcapsule in this example is the acid-base responsive microcapsule prepared in Preparation Example 7.

[0048] Example 6 An acid- and alkali-resistant and heat-resistant aramid rope conveyor belt, which is different from that in Example 1 in that the modified silicon carbide in this example is the modified silicon carbide prepared in Preparation Example 4.

[0049] Comparative Example Comparative Example 1 A high-temperature resistant aramid conveyor belt was prepared according to Example 1 in the patent document with the publication number CN103264866B and the name of "A High-temperature Resistant Aramid Conveyor Belt".

[0050] Comparative Example 2 An acid and alkali resistant and heat resistant aramid rope conveyor belt, which is different from Example 1 in that an equal amount of untreated silicon carbide is used to replace the modified silicon carbide in this comparative example.

[0051] Comparative Example 3 An acid and alkali resistant and heat resistant aramid rope conveyor belt, which is different from Example 1 in that the acid-base responsive microcapsules in this comparative example are the acid-base responsive microcapsules prepared in Preparation Example 8.

[0052] Comparative Example 4 An acid and alkali resistant and heat resistant aramid rope conveyor belt, which is different from Example 1 in that the acid-base responsive microcapsules in this comparative example are the acid-base responsive microcapsules prepared in Preparation Example 9.

[0053] Comparative Example 5 An acid and alkali resistant and heat resistant aramid rope conveyor belt, which is different from Example 1 in that the acid-base responsive microcapsules in this comparative example are the acid-base responsive microcapsules prepared in Preparation Example 10.

[0054] Performance detection test 1. Heat resistance test The heat resistance of the conveyor belts of Examples 1-6 and Comparative Examples 1-5 was tested according to the method specified in GB / T33510-2017 "Requirements and Test Methods for Heat Resistance of Rubber Covered Conveyor Belt Coverings". The conveyor belts are divided into the following three grades: Grade 1: Can withstand a test temperature of not more than 100 °C; Grade 2: Can withstand a test temperature of not more than 125 °C; Grade 3: Can withstand a test temperature of not more than 150 °C. The test results are shown in Table 2.

[0055] 2. Acid and alkali resistance test The acid and alkali resistance of the conveyor belts of Examples 1-6 and Comparative Examples 1-5 was tested according to the method specified in HG / T3782-2015 "Acid and Alkali Resistant Conveyor Belts". Among them, the acid is hydrochloric acid with a mass concentration of 18% and sulfuric acid with a mass concentration of 50%, and the alkali is sodium hydroxide with a mass concentration of 48%. The conveyor belts were soaked in the three reagents at 50 °C for 96 h respectively, and then the volume change rate and strength change rate after soaking were calculated, and the results were the average values of three groups of data. The test results are shown in Table 2.

[0056] Table 2 Test results

[0057] As can be seen from Table 2, the conveyor belts prepared in Examples 1-5 have good heat resistance, and the heat resistance grades are all Class 3. The volume expansion rates of the conveyor belts in Examples 1-5 after being resistant to acids and alkalis are between 1.23% and 1.37%, and the strength change rates are between 1.51% and 1.56%. Compared with Comparative Example 1, the volume expansion rates and strength change rates of Examples 1-5 are lower, so they have better acid and alkali resistance.

[0058] 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, the adsorption capacity for acid and alkali media and the interfacial bonding force with the rubber matrix decrease, making the erosion of the acid and alkali on the rubber relatively more serious. Therefore, the volume expansion rate and strength change rate are relatively higher than those of other examples.

[0059] In Comparative Example 2, an equal amount of untreated silicon carbide is used instead of the modified silicon carbide. The untreated silicon carbide does not have the high thermal stability and adsorption properties of the mesoporous titanium dioxide layer on the surface of the modified silicon carbide, and cannot effectively improve the thermal conductivity of the rubber like the modified silicon carbide. Therefore, its heat resistance performance is inferior to that of the examples and can only reach Class 2. The untreated silicon carbide cannot adsorb acid and alkali media and enhance the bonding force with the rubber matrix like the modified silicon carbide, and cannot effectively resist the erosion of acid and alkali on the rubber. Therefore, the volume expansion rate and strength change rate are higher than those of the examples.

[0060] In Comparative Example 3, the wall material of the acid-base responsive microcapsule is poly(methyl methacrylate-co-butyl acrylate), which does not have the acid-base response characteristics of poly(2-vinylpyridine-co-ethyl acrylate), and cannot effectively release the core material for repair when encountering acid and alkali substances, resulting in the rubber matrix being more easily damaged in an acid-base environment, thereby affecting its acid and alkali resistance performance.

[0061] The volume expansion rates and strength change rates of Comparative Examples 4 and 5 are relatively high. In Comparative Example 4, only nano-aluminum hydroxide is used as the core material, lacking the adhesion and repair effects of polydopamine; in Comparative Example 5, only polydopamine is used as the core material, lacking the acid-base neutralization effect of nano-aluminum hydroxide. In both cases, the repair effect of the microcapsule is inferior to that of the examples containing both nano-aluminum hydroxide and polydopamine. Therefore, in an acid-base environment, the damage to the rubber matrix is relatively large, and the volume expansion rate and strength change rate are relatively high. It shows that using nano-aluminum hydroxide and polydopamine as the core material can have a good synergistic effect, thereby jointly improving the acid and alkali resistance performance of the conveyor belt.

[0062] This specific embodiment is only an explanation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions 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- and alkali-resistant and heat-resistant aramid rope conveyor belt, comprising an aramid fabric 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 fabric core layer, and is characterized in that, The upper covering rubber layer and the lower covering rubber layer are made of the same acid and alkali resistant and heat resistant rubber composition, and the acid and alkali resistant and heat resistant rubber composition comprises raw materials in the following parts by weight: 50-70 parts of ethylene propylene diene monomer 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 obtained 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-base responsive microcapsules is poly(2-vinylpyridine-co-ethyl acrylate), and the core material is nano aluminum hydroxide and polydopamine.

2. The acid and alkali resistant and heat resistant aramid rope conveyor belt according to claim 1, wherein, The modified silicon carbide is prepared by the following method: (1) Add silicon carbide nanowires into a hydrofluoric acid solution, perform ultrasonic treatment at 20-30 °C for 15-30 min, then filter, take the solid phase and repeatedly rinse it with deionized water until neutral, and vacuum dry it at 60-80 °C for 8-12 h to complete the surface pretreatment of the silicon carbide nanowires; (2) Put the pretreated silicon carbide nanowires into the reaction chamber of the atomic layer deposition equipment, use titanium tetrachloride as the titanium source and water as the oxygen source, set the temperature at 150-200 °C, and maintain the reaction chamber pressure at 1-5 Pa for atomic layer deposition; (3) Take out the product after the reaction in step (2) from the reaction chamber, place it in a muffle furnace, and calcine it at 300-500 °C for 2-4 h to obtain modified silicon carbide.

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

4. A kind of acid and alkali resistant and heat resistant aramid rope conveyor belt according to claim 1, characterized in that, The acid-base responsive microcapsules are prepared by the following method: A. Mix 2-vinylpyridine, ethyl acrylate and azodiisobutyronitrile, and then carry out a stirring reaction under a nitrogen atmosphere. The reaction temperature is 65-75 °C, and the reaction time is 8-12 h. After the reaction, filter the reaction solution to obtain poly(2-vinylpyridine-co-ethyl acrylate), and then dissolve the poly(2-vinylpyridine-co-ethyl acrylate) in dimethyl sulfoxide to obtain a wall material solution; B. Add nano aluminum hydroxide and polydopamine into deionized water for ultrasonic dispersion treatment. The ultrasonic power is 200-300 W, and the ultrasonic time is 30-60 min to obtain a core material dispersion liquid; C. Mix the core material dispersion liquid with the wall material solution, add an emulsifier, stir and emulsify for 1-2 h, then carry out reduced pressure distillation at 40-50 °C for 3-5 h, and perform centrifugal separation to obtain acid-base responsive microcapsules.

5. The acid and alkali resistant and heat resistant aramid rope conveyor belt according to claim 4, wherein: In step A, the mass ratio of 2-vinylpyridine, ethyl acrylate and azodiisobutyronitrile is (10-15):(8-12):0.

1.

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

7. The acid- and alkali-resistant and heat-resistant aramid rope conveyor belt according to claim 4, wherein: In step B, the mass ratio of nano aluminum hydroxide, polydopamine and deionized water is 1:(0.8-1.2):(10-12).

8. The acid- and alkali-resistant and heat-resistant aramid rope conveyor belt according to claim 4, wherein: In step C, the mass ratio of the core material dispersion liquid to the wall material solution is 1:(1.5 - 2); the emulsifier is Tween-80, and the dosage of the emulsifier is 1.5% - 2% of the mass of the wall material solution.

9. The acid- and alkali-resistant and heat-resistant aramid rope conveyor belt according to claim 1, wherein: The anti-aging agent is any one of anti-aging agent 4010NA and anti-aging agent 4020.

10. A method for preparing an acid and alkali resistant and heat resistant aramid rope conveyor belt according to any one of claims 1-9, characterized in that, It includes the following steps: S1. Plasticate ethylene propylene diene monomer (EPDM) rubber and fluorosilicone rubber on an open mill, and control the roll temperature at 50 - 60 °C to obtain plasticated rubber. S2. Add modified silicon carbide, carbon black, zinc oxide, stearic acid, anti-aging agent, and accelerator to the plasticated rubber, and mix them using an internal mixer. The mixing temperature is 100 - 110 °C, and the time is 8 - 10 min. After the mixing is completed, add acid-base responsive microcapsules and vulcanizing agent, control the mixing temperature at 60 - 80 °C, and continue to mix for 3 - 5 min. After mixing evenly, take off the sheet to obtain an acid and alkali resistant and heat resistant rubber composition. S3. Cover the upper and lower surfaces of the aramid fabric core layer with the acid and alkali resistant and heat resistant rubber composition respectively, send it into a flat vulcanizer, and vulcanize at 160 - 170 °C and a pressure of 12 - 15 MPa for 15 - 25 min to prepare an acid and alkali resistant and heat resistant aramid rope conveyor belt.

Images