An adaptive temperature-compensated diaphragm material and method of making the same

Abstract

This invention discloses an adaptive temperature compensation diaphragm material and its preparation method, relating to the field of gas metering equipment technology. The adaptive temperature compensation diaphragm material comprises the following raw materials in parts by weight: 75-90 parts nitrile rubber, 28-48 parts modified paraffin wax, 0.8-2.2 parts modified graphene nanosheets, 1.2-2.8 parts dicumyl peroxide, 0.6-1.8 parts N-cyclohexyl-2-benzothiazole sulfenamide, 6-14 parts carbon black, 3-7 parts dioctyl phthalate, and 0.4-1.2 parts 2,6-di-tert-butyl-p-cresol. This invention eliminates the need for external sensors and electronic algorithms, achieving precise adaptive temperature compensation through the synergistic effect of modified graphene nanosheets and modified paraffin wax. The material possesses excellent tensile strength, elastic recovery rate, and aging resistance, exhibiting a stable and durable structure. The preparation process is precise and controllable, with high molding accuracy and few defects, making it suitable for various scenarios such as gas metering, and offering low cost and high reliability.

Description

Technical Field

[0001] This invention relates to the field of gas metering equipment technology, specifically to an adaptive temperature-compensated diaphragm material and its preparation method. Background Technology

[0002] Diaphragm gas meters, due to their stable and reliable performance, have become the mainstream device for gas metering. Their core metering principle involves the reciprocating expansion and contraction of a diaphragm to divide the metering chamber, measuring gas flow based on changes in diaphragm volume. However, gas volume changes significantly with temperature. In practical applications, traditional diaphragm gas meters generally use external temperature sensors to collect ambient temperature data and rely on electronic algorithms to compensate for the metering results. However, this compensation method has several drawbacks:

[0003] Insufficient compensation accuracy: There is a delay difference between the ambient temperature collected by the external sensor and the actual working temperature of the diaphragm. Especially when a large flow of gas passes through or the ambient temperature changes drastically, the temperature cannot be compensated in a timely and accurate manner, resulting in increased measurement error.

[0004] High power consumption and cost: The introduction of electronic compensation systems not only increases the power consumption of the meter, but also relies on batteries or external power sources, making it difficult to apply in scenarios without electricity; at the same time, the complex electronic components and algorithms also significantly increase manufacturing costs.

[0005] Poor reliability: The complex sensor structure and algorithms increase the risk of meter failure, resulting in high maintenance costs.

[0006] Although existing technologies have attempted to improve the elasticity of diaphragm materials, most use materials with fixed temperature coefficients, which cannot achieve dynamic adaptive temperature compensation across the entire measurement range, making it difficult to meet the requirements of high-precision gas metering. Therefore, developing a diaphragm material that can automatically adjust metering accuracy according to temperature without external intervention has become an urgent problem to be solved. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an adaptive temperature-compensated membrane material and its preparation method, thus solving the aforementioned problems.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] An adaptive temperature-compensated membrane material comprises the following raw materials in parts by weight: 75-90 parts nitrile rubber, 28-48 parts modified paraffin wax, 0.8-2.2 parts modified graphene nanosheets, 1.2-2.8 parts dicumyl peroxide, 0.6-1.8 parts N-cyclohexyl-2-benzothiazole sulfenamide, 6-14 parts carbon black, 3-7 parts dioctyl phthalate, and 0.4-1.2 parts 2,6-di-tert-butyl-p-cresol.

[0010] Furthermore, the carbon black is N330 type reinforcing carbon black with a specific surface area of ​​80-90 m². 2 / g, enhancing the reinforcing effect and improving the tensile strength and fatigue resistance of the diaphragm; the purity of the dioctyl phthalate is ≥99.5%, and the acid value is ≤0.05mgKOH / g, avoiding impurities from affecting the vulcanization reaction, ensuring uniform plasticization of the rubber compound, and improving the molding accuracy and elastic recovery of the diaphragm.

[0011] Furthermore, the modified graphene nanosheets are prepared using the following specific steps:

[0012] A1. Place a 1.0 mol / L hydrochloric acid solution in a reaction vessel, add graphene nanosheets, and stir at 300-350 r / min for 1.5 h at 30-35℃. Then slowly add a 0.5 mol / L sodium hydroxide solution to the system to adjust the pH to 8-9, and stir at 400-450 r / min for 1 h at 40-45℃. After completion, filter and wash with deionized water until the pH of the filtrate is 6.8-7.2. Dry in a vacuum drying oven at 85-95℃ for 6-8 h to obtain the first modified graphene nanosheets.

[0013] By removing impurities with hydrochloric acid solution and adjusting the pH value with sodium hydroxide, combined with gradient temperature and variable speed stirring, impurities and redundant functional groups on the surface of graphene nanosheets are effectively removed. At the same time, the surface pH is precisely controlled to a suitable range, significantly improving its surface activity and reaction compatibility. This creates favorable conditions for subsequent grafting reactions with silane coupling agents, monomers, and other substances, laying a stable foundation for modification.

[0014] A2. Take the first-modified graphene nanosheets and add them to anhydrous ethanol. Disperse them by ultrasonication at 400W for 40-60 min to form a uniform suspension. Then add polyvinylpyrrolidone and stir at 300 r / min for 10 min. Continue to add 10% by mass of silane coupling agent KH-560 ethanol solution and reflux at 70-75℃ with stirring at 400-500 r / min for 2 h. Then add N-isopropylacrylamide, N-vinylcaprolactam and azobisisobutyronitrile, raise the temperature to 80-85℃, and continue to reflux with stirring for 4-6 h. After the reaction is completed, centrifuge and wash with anhydrous ethanol 3-4 times. Dry under vacuum at 90-100℃ for 5-7 h to obtain the second-modified graphene nanosheets.

[0015] By leveraging the synergistic effect of ultrasonic dispersion and polyvinylpyrrolidone, the problem of graphene's easy agglomeration is solved, achieving uniform dispersion. Furthermore, through modification with silane coupling agent KH-560 and graft polymerization of N-isopropylacrylamide and N-vinylcaprolactam, not only is the interfacial compatibility between graphene and rubber improved, but its high thermal conductivity is also ensured, providing core support for the rapid and uniform transmission of temperature signals.

[0016] A3. Take the second modified graphene nanosheets and add them to toluene. Disperse them by ultrasonication at 400W for 20-30 min to form a stable dispersion. Dissolve nitrile rubber in toluene and add it dropwise to the dispersion at a rate of 1-2 ml / min. Stir the mixture at 300-350 r / min at 60-65℃ for 3-4 h. Then add a 0.5 mol / L isocyanate solution and continue the reaction for 2-3 h. After the reaction is complete, centrifuge and wash the product 2-3 times with toluene. Dry the product under vacuum at 80-90℃ for 4-6 h to obtain the modified graphene nanosheets.

[0017] The cross-linking of nitrile rubber and isocyanate strengthens the interfacial bonding between graphene and the rubber matrix, preventing delamination and separation during subsequent processing and use. Meanwhile, the toluene washing and vacuum drying purification process ensures the structural stability of the modified graphene nanosheets, enabling them to efficiently conduct heat in the composite system and respond to temperature changes in synergy with modified paraffin, further optimizing the material's temperature compensation performance.

[0018] Furthermore, the ratio of hydrochloric acid solution to graphene nanosheets in A1 is 400-500g:50g; the graphene nanosheets have ≤10 layers and a BET specific surface area of ​​500-1200m². 2 / g, flake diameter D50 of 1-20µm, XPS carbon-oxygen ratio ≥12, room temperature thermal conductivity ≥450W·m -1 ·K -1 Thermally conductive graphene;

[0019] Furthermore, the ratio of the first modified graphene nanosheets, anhydrous ethanol, polyvinylpyrrolidone, silane coupling agent KH-560 ethanol solution, N-isopropylacrylamide, N-vinylcaprolactam, and azobisisobutyronitrile in A2 is 40g: 200-300ml: 0.5-1.0g: 12-18ml: 8-12g: 3-5g: 0.3-0.6g.

[0020] Furthermore, the ratio of the amount of the second modified graphene nanosheets, toluene, nitrile rubber, and isocyanate solution in A3 is 30g: 200-280ml: 5-10g: 2-4ml; wherein the ratio of the amount of toluene used to disperse the second modified graphene nanosheets to dissolve the nitrile rubber is 150-200ml: 50-80ml.

[0021] Furthermore, the modified paraffin is prepared using the following specific steps:

[0022] B1. Place paraffin wax in a three-necked flask and heat and stir in a water bath at 70-80℃ until melted. Dissolve dodecylamine in anhydrous ethanol and add it dropwise to the molten paraffin wax at a rate of 1-2 ml / min. Stir at 250-300 r / min at 75-85℃ for 2-3 hours. After the reaction is complete, cool to room temperature to obtain the first modified paraffin wax.

[0023] Under water bath heating and melting conditions, dodecylamine was slowly dripped into the paraffin system and stirred at a constant temperature to allow the dodecylamine to react fully with the paraffin. This successfully introduced amino active groups into the paraffin molecular chain, breaking the original inert structure of the paraffin and significantly improving its reactivity. This process also builds a bridge for subsequent grafting reactions with modifiers such as glycidyl methacrylate.

[0024] B2. Take the first modified paraffin and add it to anhydrous ethanol. Disperse it by ultrasonication at 400W for 30-40 min to form a uniform suspension. Add a 10% (w / w) glycidyl methacrylate ethanol solution, then add potassium persulfate. Stir and reflux at 350-450 r / min at 65-75℃ for 3-5 h. After the reaction is complete, centrifuge and wash the product with anhydrous ethanol 3-4 times. Dry it under vacuum at 80-90℃ for 4-6 h to obtain the second modified paraffin.

[0025] Ultrasonic dispersion was used to uniformly suspend the first-modified paraffin, increasing the contact area with glycidyl methacrylate. Under the initiation of potassium persulfate, the two were promoted to graft copolymerization by stirring and reflux. This not only enhanced the compatibility of paraffin with the organic phase, but also improved its thermal stability, avoiding the problem of excessive melting and loss of paraffin in high-temperature processing or use environments.

[0026] B3. Take the second modified paraffin and add it to toluene. Disperse it by ultrasonication at 400W for 20-30 minutes to form a stable dispersion. Dissolve nitrile rubber in toluene and slowly add it dropwise to the dispersion at a rate of 1 ml / min. At the same time, add a 0.4 mol / L hexamethylenediamine solution and stir the mixture at 300-400 r / min at 60-70℃ for 2-3 hours. After the reaction is complete, centrifuge the mixture and wash the product with toluene 2-3 times. Dry the product under vacuum at 75-85℃ for 3-5 hours to obtain the modified paraffin.

[0027] By employing ultrasonic dispersion and slow dropwise addition processes, modified paraffin wax and nitrile rubber are thoroughly mixed. Then, through the cross-linking effect of hexamethylenediamine, the interfacial bonding between paraffin wax and the rubber matrix is ​​strengthened. Subsequent purification treatments, such as toluene washing and vacuum drying, ensure the purity and structural stability of the modified paraffin wax, allowing its phase change properties to be stably expressed. In synergy with modified graphene nanosheets, it achieves adaptive temperature regulation over a wide temperature range, ensuring the consistent performance of the membrane under different temperature environments.

[0028] Furthermore, the ratio of paraffin, dodecylamine, and anhydrous ethanol in B1 is 120g: 8-15g: 50-80ml.

[0029] Furthermore, the ratio of the first modified paraffin, anhydrous ethanol, glycidyl methacrylate ethanol solution, and potassium persulfate in B2 is 90g: 200-300ml: 10-18ml: 0.3-0.6g.

[0030] Furthermore, the ratio of the amount of the second modified paraffin, toluene, nitrile rubber, and hexamethylenediamine solution in B3 is 60g: 200-330ml: 5-10g: 2-4ml; wherein the ratio of the amount of toluene used to disperse the second modified paraffin to dissolve the nitrile rubber is 150-250ml: 50-80ml.

[0031] A method for preparing an adaptive temperature-compensated diaphragm material specifically includes the following steps:

[0032] S1. Mix 0.8-2.2 parts of modified graphene nanosheets with 28-48 parts of modified paraffin wax in a high-speed mixer. Mix for 35-45 minutes at 65-75℃ and 900-1100 r / min. After cooling to room temperature and solidification, pulverize and select particles with a particle size of 5-50 μm to obtain paraffin / graphene composite high-performance temperature-responsive particles. High-temperature and high-speed mixing promotes the full fusion of modified graphene nanosheets and modified paraffin wax to form a uniform composite structure. Sieving controls the particle size to ensure particle dispersion and avoid the influence of uneven particle size on the consistency of temperature response, laying the foundation for adaptive temperature compensation.

[0033] S2. Preheat the nitrile rubber in an oven at 62-68℃ for 2.5-3.5 hours to improve the plasticizing effect and reduce the difficulty of subsequent mixing; take dicumyl peroxide, N-cyclohexyl-2-benzothiazole sulfenamide, carbon black, dioctyl phthalate, and 2,6-di-tert-butyl-p-cresol, mix them evenly, and grind them through a 200-mesh sieve to ensure uniform dispersion, avoid particulate impurities causing film defects, optimize vulcanization and reinforcement effects, and set aside for later use;

[0034] S3. Add 75-90 parts of preheated nitrile rubber to a mixer, set the mixing temperature to 82-98℃, the speed to 55-75 r / min, and masticate for 6-9 minutes. Add 2-4 parts of carbon black in the later stage of mastication. Reduce the mixing temperature to 75-85℃, add 1.2-2.8 parts of pretreated dicumyl peroxide, 0.6-1.8 parts of N-cyclohexyl-2-benzothiazole sulfenamide, 4-10 parts of carbon black, 3-7 parts of dioctyl phthalate, and 0.4-1.2 parts of 2,6-di-tert-butyl-p-cresol, and continue mixing for 9-11 minutes, venting every 2.5 minutes. Segmented temperature control and variable speed mixing first improve the plasticity of the rubber, and then promote the uniform dispersion of the additives. Adding carbon black in batches avoids agglomeration and enhances the reinforcing effect.

[0035] S4. Slowly add the temperature-responsive particles prepared in S1. After the addition is complete, raise the temperature to 95-105℃ and rotate at 65-85 r / min. Continue mixing for 18-28 min, during which the Mooney viscosity of the rubber compound is monitored in real time and controlled at 45-55. After mixing, transfer the rubber compound to an open mill and pass it through a thin mill 4-6 times at 72-82℃. Adjust the roller gap to 0.6-1.1 mm and produce a mixed rubber sheet with a thickness of 3.5-4.5 mm.

[0036] S5. Preheat the flat vulcanizing machine, setting both the upper and lower mold temperatures to 135-145℃ for 35-45 minutes, ensuring mold temperature fluctuations ≤ ±1℃. Place the mixed rubber sheet into the mold, and after closing the mold, apply a pre-compression of 6-8MPa for 6-8 minutes, then gradually increase the pressure to 8-14MPa, maintaining stable pressure while maintaining the mold temperature for vulcanization. The total vulcanization time should be controlled at 40-55 minutes. During vulcanization, vent air for 10-15 seconds every 7-9 minutes. Segmented pressure increase and pre-compression remove residual air, promoting the filling of the mold with rubber. Regular venting removes gases generated during vulcanization, avoiding porosity defects. Precise temperature and time control ensures sufficient vulcanization crosslinking, improving the strength and stability of the film structure.

[0037] S6. After vulcanization, keep the pressure constant and cool down to room temperature at a rate of 5℃ / min to reduce dimensional shrinkage and deformation, and ensure the dimensional accuracy of the diaphragm. Open the mold and take out the diaphragm blank. After trimming, cleaning and drying, the diaphragm material with adaptive temperature compensation is obtained.

[0038] Furthermore, the Mooney viscosity was measured according to ASTM D1646 standard by preheating the large rotor for 1 minute and testing for 4 minutes at 100°C.

[0039] Furthermore, during the mixing process of the high-speed mixer in S1, nitrogen gas is introduced to purge the particles every 10 minutes, with each purging lasting 30 seconds. Nitrogen purging isolates the particles from air, preventing oxidation of the temperature-responsive particles during high-temperature mixing, ensuring the structural stability of the modified graphene nanosheets and modified paraffin, ensuring that the temperature response performance of the composite particles is not affected by oxidation, and maintaining the accuracy of the membrane's adaptive temperature compensation.

[0040] This invention provides an adaptive temperature-compensated diaphragm material and its preparation method, which has the following beneficial effects:

[0041] 1. Material composite synergistic innovation for superior compensation accuracy: Using nitrile rubber as a stable matrix, innovatively introducing three-step modified graphene nanosheets and paraffin wax to form composite temperature-responsive particles. The high thermal conductivity of graphene rapidly homogenizes the ambient temperature, while the modified paraffin wax undergoes a solid-liquid phase transition, resulting in volume expansion and reduced micro-area stiffness. The synergy of the two allows the overall elastic modulus of the diaphragm to be slightly adjustable with temperature, thereby automatically correcting the effective volume of the metering cavity and offsetting the fluctuation of the gas volume with temperature.

[0042] 2. Design without external intervention, resulting in superior practicality: Completely abandoning the traditional compensation mode of diaphragm gas meters that relies on external temperature sensors, electronic algorithms, and power supplies, this design autonomously responds to temperature changes solely through the material's own physical properties, achieving real-time compensation without additional energy consumption. This design not only simplifies the overall structure of the gas meter, reduces the risk of electronic component failure, and significantly reduces maintenance costs, but also adapts to special scenarios such as power outages and harsh environments, improving the reliability and applicability of the equipment, while avoiding metering errors caused by sensor temperature acquisition delays.

[0043] 3. The preparation process is highly compatible with mass production and offers greater flexibility in application scenarios: The preparation process is highly compatible with existing rubber product manufacturing processes. Only precise addition of temperature-responsive particles during the mixing stage and fine-tuning of parameters such as vulcanization temperature and pressure are required. No large-scale modification of production equipment is needed, making industrialization easier and controlling the increase in manufacturing costs. Furthermore, by adjusting parameters such as the ratio of modified graphene nanosheets to paraffin wax and particle size, the process can be customized to adapt to different temperature ranges, meeting the diverse needs of gas metering scenarios. In addition, precise temperature control, segmented mixing, and nitrogen protection in the process ensure the stability and consistency of material performance, further enhancing the feasibility of mass production. Detailed Implementation

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1: Preparation of an adaptive temperature-compensated membrane material. The specific preparation steps are as follows:

[0046] S1. Mix 0.8 parts of modified graphene nanosheets with 28 parts of modified paraffin wax in a high-speed mixer and mix for 35 minutes at 65℃ and 900 r / min. After cooling to room temperature and solidification, put the mixture into a pulverizer and sieve to select particles with a particle size of 5-50 μm to obtain paraffin / graphene composite high-performance temperature-responsive particles.

[0047] S2. Preheat the nitrile rubber in a 62℃ oven for 2.5 hours; take dicumyl peroxide, N-cyclohexyl-2-benzothiazole sulfenamide, carbon black, dioctyl phthalate, and 2,6-di-tert-butyl-p-cresol, mix them evenly, grind them through a 200-mesh sieve, and set aside.

[0048] S3. Add 75 parts of preheated nitrile rubber to a mixer, set the mixing temperature to 82℃, the speed to 55 r / min, and plasticize for 6 min. Add 2 parts of carbon black in the later stage of plasticizing. Reduce the mixing temperature to 75℃, add 1.2 parts of pretreated dicumyl peroxide, 0.6 parts of N-cyclohexyl-2-benzothiazole sulfenamide, 4 parts of carbon black, 3 parts of dioctyl phthalate, and 0.4 parts of 2,6-di-tert-butyl-p-cresol, and continue mixing for 9 min, venting once every 2.5 min.

[0049] S4. Slowly add the temperature-responsive particles prepared in S1. After the addition is complete, raise the temperature to 95℃, rotate the speed to 65r / min, and continue mixing for 18min. During this period, monitor the Mooney viscosity of the rubber compound in real time and control the Mooney viscosity to 45-55. After mixing, transfer the rubber compound to a two-roll mill, pass it through a thin mill 4 times at 72℃, adjust the roller gap to 0.6mm, and obtain a mixed rubber sheet with a thickness of 3.5mm.

[0050] S5. Preheat the flat vulcanizing machine. Set the temperature of both the upper and lower molds to 135℃ and the preheating time to 35 minutes, ensuring that the mold temperature fluctuation is ≤±1℃. Place the mixed rubber sheet into the mold. After closing the mold, apply a pressure of 6MPa for 6 minutes, then gradually increase the pressure to 8MPa and keep the pressure stable. At the same time, maintain the set temperature of the mold for the vulcanization reaction. The total vulcanization time is controlled within 40 minutes. During the vulcanization process, exhaust air for 10 seconds every 7 minutes.

[0051] S6. After vulcanization, keep the pressure constant and cool down to room temperature at a rate of 5℃ / min. Open the mold and take out the diaphragm blank. After trimming, cleaning and drying, the diaphragm material with adaptive temperature compensation is obtained.

[0052] Example 2: Preparation of an adaptive temperature-compensated membrane material. The specific preparation steps are as follows:

[0053] S1. Mix 2.2 parts of modified graphene nanosheets with 48 parts of modified paraffin wax in a high-speed mixer and mix for 45 min at 75℃ and 1100 r / min. After cooling to room temperature and solidification, put the mixture into a pulverizer and sieve to select particles with a particle size of 5-50 μm to obtain paraffin / graphene composite high-performance temperature-responsive particles.

[0054] S2. Preheat the nitrile rubber in a 68℃ oven for 3.5 hours; take dicumyl peroxide, N-cyclohexyl-2-benzothiazole sulfenamide, carbon black, dioctyl phthalate, and 2,6-di-tert-butyl-p-cresol, mix them evenly, grind them through a 200-mesh sieve, and set aside.

[0055] S3. Add 90 parts of preheated nitrile rubber to a mixer, set the mixing temperature to 98℃, the speed to 75 r / min, and plasticize for 9 min. Add 4 parts of carbon black in the later stage of plasticizing. Reduce the mixing temperature to 85℃, add 2.8 parts of pretreated dicumyl peroxide, 1.8 parts of N-cyclohexyl-2-benzothiazole sulfenamide, 10 parts of carbon black, 7 parts of dioctyl phthalate, and 1.2 parts of 2,6-di-tert-butyl-p-cresol, and continue mixing for 11 min, venting once every 2.5 min.

[0056] S4. Slowly add the temperature-responsive particles prepared in S1. After the addition is complete, raise the temperature to 105℃, rotate the speed to 85r / min, and continue mixing for 28min. During this period, monitor the Mooney viscosity of the rubber compound in real time and control the Mooney viscosity to 45-55. After mixing, transfer the rubber compound to a two-roll mill, pass it through a thin mill 6 times at 82℃, adjust the roller gap to 1.1mm, and obtain a mixed rubber sheet with a thickness of 4.5mm.

[0057] S5. Preheat the flat vulcanizing machine. Set the temperature of both the upper and lower molds to 145℃ and the preheating time to 45 minutes, ensuring that the mold temperature fluctuation is ≤±1℃. Place the mixed rubber sheet into the mold. After closing the mold, apply a pressure of 8MPa for 8 minutes, then gradually increase the pressure to 14MPa and keep the pressure stable. At the same time, maintain the set temperature of the mold for the vulcanization reaction. The total vulcanization time is controlled at 55 minutes. During the vulcanization process, exhaust air for 15 seconds every 9 minutes.

[0058] S6. After vulcanization, keep the pressure constant and cool down to room temperature at a rate of 5℃ / min. Open the mold and take out the diaphragm blank. After trimming, cleaning and drying, the diaphragm material with adaptive temperature compensation is obtained.

[0059] Example 3: Preparation of an adaptive temperature-compensated membrane material. The specific preparation steps are as follows:

[0060] S1. Mix 1.5 parts of modified graphene nanosheets with 38 parts of modified paraffin wax in a high-speed mixer and mix for 40 min at 70℃ and 1000 r / min. After cooling to room temperature and solidification, put the mixture into a pulverizer and sieve to select particles with a particle size of 5-50 μm to obtain paraffin / graphene composite high-performance temperature-responsive particles.

[0061] S2. Preheat the nitrile rubber in a 65℃ oven for 3 hours; take dicumyl peroxide, N-cyclohexyl-2-benzothiazole sulfenamide, carbon black, dioctyl phthalate, and 2,6-di-tert-butyl-p-cresol, mix them evenly, grind them through a 200-mesh sieve, and set aside.

[0062] S3. Add 82 parts of preheated nitrile rubber to a mixer, set the mixing temperature to 90℃, the speed to 65 r / min, and plasticize for 7 min. Add 3 parts of carbon black in the later stage of plasticizing. Reduce the mixing temperature to 80℃, add 2 parts of pretreated dicumyl peroxide, 1.2 parts of N-cyclohexyl-2-benzothiazole sulfenamide, 6 parts of carbon black, 5 parts of dioctyl phthalate, and 0.8 parts of 2,6-di-tert-butyl-p-cresol. Continue mixing for 10 min, venting once every 2.5 min.

[0063] S4. Slowly add the temperature-responsive particles prepared in S1. After the addition is complete, raise the temperature to 100℃, rotate the speed at 75r / min, and continue mixing for 23min. During this period, monitor the Mooney viscosity of the rubber compound in real time and control the Mooney viscosity between 45-55. After mixing, transfer the rubber compound to a two-roll mill and pass it through a thin mill 5 times at 77℃. Adjust the roller gap to 0.8mm and get a mixed rubber sheet with a thickness of 4mm.

[0064] S5. Preheat the flat vulcanizing machine. Set the temperature of both the upper and lower molds to 140℃ and the preheating time to 40 minutes, ensuring that the mold temperature fluctuation is ≤±1℃. Place the mixed rubber sheet into the mold. After closing the mold, apply a pressure of 7MPa for 7 minutes, then gradually increase the pressure to 11MPa and keep the pressure stable. At the same time, maintain the set temperature of the mold for vulcanization reaction. The total vulcanization time is controlled at 47 minutes. During the vulcanization process, exhaust air for 12 seconds every 8 minutes.

[0065] S6. After vulcanization, keep the pressure constant and cool down to room temperature at a rate of 5℃ / min. Open the mold and take out the diaphragm blank. After trimming, cleaning and drying, the diaphragm material with adaptive temperature compensation is obtained.

[0066] Example 4: Preparation of modified graphene nanosheets. The specific preparation steps are as follows:

[0067] A1. Place 400g of 1.0mol / L hydrochloric acid solution in a reaction vessel, add 50g of graphene nanosheets, and stir at 300r / min for 1.5h at 30℃. Then slowly add 0.5mol / L sodium hydroxide solution to the system to adjust the pH to 8, and stir at 400r / min for 1h at 40℃. After the reaction, filter and wash with deionized water until the pH of the filtrate is 6.8. Dry in a vacuum drying oven at 85℃ for 6h to obtain the first modified graphene nanosheets.

[0068] A2. Take 40g of the first-modified graphene nanosheets and add them to 200ml of anhydrous ethanol. Disperse the mixture by ultrasonication at 400W for 40min to form a uniform suspension. Then add 0.5g of polyvinylpyrrolidone and stir at 300r / min for 10min. Continue to add 12ml of 10% (w / w) silane coupling agent KH-560 ethanol solution and reflux at 70℃ with stirring at 400r / min for 2h. Then add 8g of N-isopropylacrylamide, 3g of N-vinylcaprolactam and 0.3g of azobisisobutyronitrile, raise the temperature to 80℃, and continue stirring and reflux for 4h. After the reaction is completed, centrifuge and wash three times with anhydrous ethanol. Dry under vacuum at 90℃ for 5h to obtain the second-modified graphene nanosheets.

[0069] A3. Take 30g of the second modified graphene nanosheets and add them to 150ml of toluene. Disperse the mixture by ultrasonication at 400W for 20min to form a stable dispersion. Dissolve 5g of nitrile rubber in 50ml of toluene and add it dropwise to the dispersion at a rate of 1ml / min. Stir the mixture at 300r / min at 60℃ for 3h. Then add 2ml of 0.5mol / L isocyanate solution and continue the reaction for 2h. After the reaction is complete, centrifuge the mixture, wash the product twice with toluene, and vacuum dry it at 80℃ for 4h to obtain the modified graphene nanosheets.

[0070] Example 5: Preparation of modified graphene nanosheets. The specific preparation steps are as follows:

[0071] A1. Place 500g of 1.0mol / L hydrochloric acid solution in a reaction vessel, add 50g of graphene nanosheets, and stir at 350r / min for 1.5h at 35℃. Then slowly add 0.5mol / L sodium hydroxide solution to the system to adjust the pH to 9, and stir at 450r / min for 1h at 45℃. After the reaction, filter and wash with deionized water until the pH of the filtrate is 7.2. Dry in a vacuum drying oven at 95℃ for 8h to obtain the first modified graphene nanosheets.

[0072] A2. Take 40g of the first-modified graphene nanosheets and add them to 300ml of anhydrous ethanol. Disperse the mixture by ultrasonication at 400W for 60min to form a uniform suspension. Then add 1.0g of polyvinylpyrrolidone and stir at 300r / min for 10min. Continue to add 18ml of 10% (w / w) silane coupling agent KH-560 ethanol solution and reflux at 75℃ with stirring at 500r / min for 2h. Then add 12g of N-isopropylacrylamide, 5g of N-vinylcaprolactam and 0.6g of azobisisobutyronitrile, raise the temperature to 85℃, and continue to reflux with stirring for 6h. After the reaction is completed, centrifuge and wash with anhydrous ethanol 4 times. Dry under vacuum at 100℃ for 7h to obtain the second-modified graphene nanosheets.

[0073] A3. Take 30g of the second modified graphene nanosheets and add them to 200ml of toluene. Disperse the mixture by ultrasonication at 400W for 30min to form a stable dispersion. Dissolve 10g of nitrile rubber in 80ml of toluene and add it dropwise to the dispersion at a rate of 2ml / min. Stir the mixture at 350r / min at 65℃ for 4h. Then add 4ml of 0.5mol / L isocyanate solution and continue the reaction for 3h. After the reaction is complete, centrifuge the mixture, wash the product three times with toluene, and dry it under vacuum at 90℃ for 6h to obtain the modified graphene nanosheets.

[0074] Example 6: Preparation of modified paraffin. The specific preparation steps are as follows:

[0075] B1. Place 120g of paraffin wax in a three-necked flask and heat and stir in a 70℃ water bath until melted. Dissolve 8g of dodecylamine in 50ml of anhydrous ethanol and add it dropwise to the molten paraffin wax at a rate of 1ml / min. Stir at 250r / min for 2h at 75℃. After the reaction is complete, cool to room temperature to obtain the first modified paraffin wax.

[0076] B2. Take 90g of the first modified paraffin and add it to 200ml of anhydrous ethanol. Disperse it by ultrasonication at 400W for 30min to form a uniform suspension. Add 10ml of 10% glycidyl methacrylate ethanol solution and then add 0.3g of potassium persulfate. Stir and reflux at 350r / min at 65℃ for 3h. After the reaction is completed, centrifuge and separate the product. Wash the product three times with anhydrous ethanol and vacuum dry at 80℃ for 4h to obtain the second modified paraffin.

[0077] B3. Take 60g of the second modified paraffin and add it to 150ml of toluene. Disperse it by ultrasonication at 400W for 20min to form a stable dispersion. Take 5g of nitrile rubber and dissolve it in 50ml of toluene. Slowly add the mixture to the dispersion at a rate of 1ml / min. At the same time, add 2ml of 0.4mol / L hexamethylenediamine solution. Stir the mixture at 300r / min at 60℃ for 2h. After the reaction is complete, centrifuge the product, wash it twice with toluene, and dry it under vacuum at 75℃ for 3h to obtain the modified paraffin.

[0078] Example 7: Preparation of modified paraffin wax. The specific preparation steps are as follows:

[0079] B1. Place 120g of paraffin wax in a three-necked flask and heat and stir in an 80℃ water bath until melted; dissolve 15g of dodecylamine in 80ml of anhydrous ethanol and add it dropwise to the molten paraffin wax at a rate of 2ml / min; stir at 300r / min for 3h at 85℃; after the reaction is complete, cool to room temperature to obtain the first modified paraffin wax.

[0080] B2. Take 90g of the first modified paraffin and add it to 300ml of anhydrous ethanol. Disperse it by ultrasonication at 400W for 40min to form a uniform suspension. Add 18ml of 10% glycidyl methacrylate ethanol solution and then add 0.6g of potassium persulfate. Stir and reflux at 75℃ and 450r / min for 5h. After the reaction is completed, centrifuge and wash the product 4 times with anhydrous ethanol. Dry it under vacuum at 90℃ for 6h to obtain the second modified paraffin.

[0081] B3. Take 60g of the second modified paraffin and add it to 250ml of toluene. Disperse it by ultrasonication at 400W for 30min to form a stable dispersion. Take 10g of nitrile rubber and dissolve it in 80ml of toluene. Slowly add the mixture to the dispersion at a rate of 1ml / min. At the same time, add 4ml of 0.4mol / L hexamethylenediamine solution. Stir the mixture at 70℃ and 400r / min for 3h. After the reaction is complete, centrifuge the product, wash it three times with toluene, and vacuum dry it at 85℃ for 5h to obtain the modified paraffin.

[0082] Comparative Example 1: An adaptive temperature-compensated membrane material was prepared. The specific preparation steps are as follows:

[0083] The remaining steps remain the same, except that the modified graphene nanosheets prepared in Example 4 and used in Example 3 are replaced with unmodified graphene nanosheets to prepare an adaptive temperature-compensated film material.

[0084] Comparative Example 2: Preparation of an adaptive temperature-compensated membrane material. The specific preparation steps are as follows:

[0085] The remaining steps remain the same, except that the modified paraffin prepared in Example 7 and used in Example 3 are replaced with unmodified paraffin to prepare an adaptive temperature-compensated membrane material.

[0086] Comparative Example 3: An adaptive temperature-compensated membrane material was prepared. The specific preparation steps are as follows:

[0087] The remaining steps remain unchanged, except that the modified graphene nanosheets prepared in Example 4 used in Example 3 are replaced with unmodified graphene nanosheets, and the modified paraffin wax prepared in Example 7 is replaced with unmodified paraffin wax, so as to prepare an adaptive temperature-compensated film material.

[0088] Performance testing

[0089] Test item Test standard / method Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Temperature compensation error According to GB / T 6968-2019 5.3.4, constant temperature-10℃, 40℃ for 4h respectively, three-point ventilation of qmax, 0.2qmax, qmin for 1h, δ=|(Vm-Vs) / Vs|max×100% ≤1.0% ≤0.8% ≤0.5% ≤2.2% ≤2.0% ≤3.1% Tensile strength (MPa) GB / T 528-2009 17.8 19.2 20.5 15.1 16.3 14.0 Elastic recovery rate (%) GB / T 1681-2009 83 86 88 76 78 73 Tensile strength retention rate after heat aging (100℃×72h, normal pressure, room temperature for 16-96h) (%) GB / T 3512-2014 80 83 85 70 72 66

[0090] Performance test results show that the adaptive temperature compensation film materials prepared in Examples 1-3 have significantly better overall performance than those in Comparative Examples 1-3: the temperature compensation error is ≤1.0%, with Example 3 being the best at only ≤0.5%, while the comparative examples using unmodified graphene nanosheets, unmodified paraffin, or neither have the highest temperature compensation error, reaching 3.1%; in terms of tensile strength, Example 3 reaches 20.5 MPa, while the comparative examples have the highest at 16.3 MPa; the elastic recovery rate of the examples is ≥83%, while that of the comparative examples is ≤78%; the tensile strength retention rate after thermal aging is ≥80% of the examples, while that of the comparative examples is the lowest at only 66%, indicating that the synergistic effect of modified graphene nanosheets and modified paraffin can effectively improve the temperature compensation accuracy, mechanical properties, and anti-aging ability of the film.

[0091] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A diaphragm material with adaptive temperature compensation, characterized in that: It contains the following raw materials in parts by weight: 75-90 parts nitrile rubber, 28-48 parts modified paraffin, 0.8-2.2 parts modified graphene nanosheets, 1.2-2.8 parts dicumyl peroxide, 0.6-1.8 parts N-cyclohexyl-2-benzothiazole sulfenamide, 6-14 parts carbon black, 3-7 parts dioctyl phthalate, and 0.4-1.2 parts 2,6-di-tert-butyl-p-cresol.

2. The adaptive temperature compensation diaphragm material according to claim 1, characterized in that: The carbon black is N330 type reinforcing carbon black, with a specific surface area of ​​80-90 m². 2 / g; the purity of the dioctyl phthalate is ≥99.5%, and the acid value is ≤0.05mgKOH / g.

3. The adaptive temperature compensation diaphragm material according to claim 1, characterized in that: The modified graphene nanosheets are prepared using the following specific steps: A1. Place a 1.0 mol / L hydrochloric acid solution in a reaction vessel, add graphene nanosheets, and stir at 300-350 r / min for 1.5 h at 30-35℃. Then slowly add a 0.5 mol / L sodium hydroxide solution to the system to adjust the pH to 8-9, and stir at 400-450 r / min for 1 h at 40-45℃. After completion, filter and wash with deionized water until the pH of the filtrate is 6.8-7.

2. Dry in a vacuum drying oven at 85-95℃ for 6-8 h to obtain the first modified graphene nanosheets. A2. Take the first-modified graphene nanosheets and add them to anhydrous ethanol. Disperse them by ultrasonication at 400W for 40-60 min to form a uniform suspension. Then add polyvinylpyrrolidone and stir at 300 r / min for 10 min. Continue to add 10% by mass of silane coupling agent KH-560 ethanol solution and reflux at 70-75℃ with stirring at 400-500 r / min for 2 h. Then add N-isopropylacrylamide, N-vinylcaprolactam and azobisisobutyronitrile, raise the temperature to 80-85℃, and continue to reflux with stirring for 4-6 h. After the reaction is completed, centrifuge and wash with anhydrous ethanol 3-4 times. Dry under vacuum at 90-100℃ for 5-7 h to obtain the second-modified graphene nanosheets. A3. Take the second modified graphene nanosheets and add them to toluene. Disperse them by ultrasonication at 400W for 20-30 min to form a stable dispersion. Dissolve nitrile rubber in toluene and add it dropwise to the dispersion at a rate of 1-2 ml / min. Stir the mixture at 300-350 r / min at 60-65℃ for 3-4 h. Then add a 0.5 mol / L isocyanate solution and continue the reaction for 2-3 h. After the reaction is complete, centrifuge and wash the product 2-3 times with toluene. Dry the product under vacuum at 80-90℃ for 4-6 h to obtain the modified graphene nanosheets.

4. The adaptive temperature compensation diaphragm material according to claim 3, characterized in that: The ratio of hydrochloric acid solution to graphene nanosheets in A1 is 400-500g:50g; the graphene nanosheets have ≤10 layers, a BET specific surface area of ​​500-1200m² / g, a sheet diameter D50 of 1-20µm, an XPS carbon-oxygen ratio ≥12, and a room temperature thermal conductivity ≥450W·m. -1 ·K -1 Thermally conductive graphene; The ratio of the first modified graphene nanosheets, anhydrous ethanol, polyvinylpyrrolidone, silane coupling agent KH-560 ethanol solution, N-isopropylacrylamide, N-vinylcaprolactam, and azobisisobutyronitrile in A2 is 40g: 200-300ml: 0.5-1.0g: 12-18ml: 8-12g: 3-5g: 0.3-0.6g; The ratio of the amount of the second modified graphene nanosheets, toluene, nitrile rubber, and isocyanate solution in A3 is 30g: 200-280ml: 5-10g: 2-4ml; wherein the ratio of the amount of toluene used to disperse the second modified graphene nanosheets to dissolve the nitrile rubber is 150-200ml: 50-80ml.

5. The adaptive temperature compensation diaphragm material according to claim 1, characterized in that: The modified paraffin is prepared using the following specific steps: B1. Place paraffin wax in a three-necked flask and heat and stir in a water bath at 70-80℃ until melted. Dissolve dodecylamine in anhydrous ethanol and add it dropwise to the molten paraffin wax at a rate of 1-2 ml / min. Stir at 250-300 r / min at 75-85℃ for 2-3 hours. After the reaction is complete, cool to room temperature to obtain the first modified paraffin wax. B2. Take the first modified paraffin and add it to anhydrous ethanol. Disperse it by ultrasonication at 400W for 30-40 minutes to form a uniform suspension. Add a 10% (w / w) solution of glycidyl methacrylate in ethanol, then add potassium persulfate, and stir and reflux at 350-450 r / min at 65-75℃ for 3-5 h. After the reaction is complete, centrifuge and wash the product 3-4 times with anhydrous ethanol, and vacuum dry at 80-90℃ for 4-6 h to obtain the second modified paraffin. B3. Take the second modified paraffin and add it to toluene. Disperse it by ultrasonication at 400W for 20-30 minutes to form a stable dispersion. Dissolve nitrile rubber in toluene and slowly add it dropwise to the dispersion at a rate of 1 ml / min. At the same time, add a 0.4 mol / L hexamethylenediamine solution and stir the mixture at 300-400 r / min at 60-70℃ for 2-3 hours. After the reaction is complete, centrifuge the mixture and wash the product with toluene 2-3 times. Dry the product under vacuum at 75-85℃ for 3-5 hours to obtain the modified paraffin.

6. The adaptive temperature compensation diaphragm material according to claim 5, characterized in that: The ratio of paraffin, dodecylamine, and anhydrous ethanol in B1 is 120g: 8-15g: 50-80ml; The ratio of the first modified paraffin, anhydrous ethanol, glycidyl methacrylate ethanol solution, and potassium persulfate in B2 is 90g: 200-300ml: 10-18ml: 0.3-0.6g; The ratio of the amount of the second modified paraffin, toluene, nitrile rubber, and hexamethylenediamine solution in B3 is 60g: 200-330ml: 5-10g: 2-4ml; wherein the ratio of the amount of toluene used to disperse the second modified paraffin to dissolve the nitrile rubber is 150-250ml: 50-80ml.

7. A method for preparing an adaptive temperature-compensated diaphragm material, characterized in that: Specifically, it includes the following steps: S1. Mix 0.8-2.2 parts of modified graphene nanosheets with 28-48 parts of modified paraffin wax, place them in a high-speed mixer, mix for 35-45 minutes at 65-75℃ and 900-1100 r / min, cool to room temperature and solidify, then put them into a pulverizer and sieve to select particles with a particle size of 5-50 μm to obtain paraffin / graphene composite high-performance temperature-responsive particles. S2. Preheat the nitrile rubber in an oven at 62-68℃ for 2.5-3.5 hours; take dicumyl peroxide, N-cyclohexyl-2-benzothiazole sulfenamide, carbon black, dioctyl phthalate, and 2,6-di-tert-butyl-p-cresol, mix them evenly, and grind them through a 200-mesh sieve for later use. S3. Add 75-90 parts of preheated nitrile rubber to an internal mixer, set the mixing temperature to 82-98℃, the speed to 55-75 r / min, and plasticize for 6-9 min. Add 2-4 parts of carbon black in the later stage of plasticizing. Reduce the mixing temperature to 75-85℃, add 1.2-2.8 parts of pretreated dicumyl peroxide, 0.6-1.8 parts of N-cyclohexyl-2-benzothiazole sulfenamide, 4-10 parts of carbon black, 3-7 parts of dioctyl phthalate, and 0.4-1.2 parts of 2,6-di-tert-butyl-p-cresol, and continue mixing for 9-11 min, venting the gas every 2.5 min. S4. Slowly add the temperature-responsive particles prepared in S1. After the addition is complete, raise the temperature to 95-105℃ and rotate at 65-85 r / min. Continue mixing for 18-28 min, during which the Mooney viscosity of the rubber compound is monitored in real time and controlled at 45-55. After mixing, transfer the rubber compound to an open mill and pass it through a thin mill 4-6 times at 72-82℃. Adjust the roller gap to 0.6-1.1 mm and produce a mixed rubber sheet with a thickness of 3.5-4.5 mm. S5. Preheat the flat vulcanizing machine. Set the temperature of both the upper and lower molds to 135-145℃ and the preheating time to 35-45 minutes, ensuring that the mold temperature fluctuation is ≤±1℃. Place the mixed rubber sheet into the mold. After closing the mold, apply a pressure of 6-8MPa for 6-8 minutes, then gradually increase the pressure to 8-14MPa and keep the pressure stable. At the same time, maintain the set temperature of the mold for the vulcanization reaction. The total vulcanization time should be controlled at 40-55 minutes. During the vulcanization process, vent air for 10-15 seconds every 7-9 minutes. S6. After vulcanization, keep the pressure constant and cool down to room temperature at a rate of 5℃ / min. Open the mold and take out the diaphragm blank. After trimming, cleaning and drying, the diaphragm material with adaptive temperature compensation is obtained.

8. The method for preparing an adaptive temperature-compensated diaphragm material according to claim 7, characterized in that: The Mooney viscosity was measured according to ASTM D1646 standard, using a large rotor preheated for 1 minute and tested for 4 minutes at 100°C.

9. The method for preparing an adaptive temperature-compensated diaphragm material according to claim 7, characterized in that: During the mixing process of the high-speed mixer in S1, nitrogen gas is introduced to purge once every 10 minutes, and each purging time is 30 seconds.