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CN-122011659-A - Modified polytetrafluoroethylene material for electrolytic tank and preparation method thereof

CN122011659ACN 122011659 ACN122011659 ACN 122011659ACN-122011659-A

Abstract

The invention provides a modified polytetrafluoroethylene material for an electrolytic tank and a preparation method thereof, wherein the raw materials of the modified polytetrafluoroethylene material for the electrolytic tank comprise, by weight, 100-120 parts of modified polytetrafluoroethylene resin, 5-15 parts of polyimide resin, 3-8 parts of fluorinated ceramic microspheres and 0.5-5 parts of fluorinated graphene. Through in-situ copolymerization of modified resin, high-speed mixing of each component, compacting and step sintering, the multi-component composite cooperation ensures that the creep relaxation resistance, compression rebound resilience, mechanical strength and gas tightness of the material are greatly improved while the excellent corrosion resistance of PTFE is maintained, and the material is particularly suitable for sealing long service life of alkaline or PEM electrolytic water hydrogen production electrolytic tanks and other severe working conditions.

Inventors

  • Shang Qingjia
  • WANG CHAOYI
  • MA SHUJING

Assignees

  • 山东金纪氟塑工程有限公司

Dates

Publication Date
20260512
Application Date
20260226

Claims (10)

  1. 1. The modified polytetrafluoroethylene material for the electrolytic tank is characterized by comprising, by weight, 100-120 parts of modified polytetrafluoroethylene resin, 5-15 parts of polyimide resin, 3-8 parts of fluorinated ceramic microspheres and 0.5-5 parts of fluorinated graphene.
  2. 2. The modified polytetrafluoroethylene material for the electrolytic tank according to claim 1, wherein the modified polytetrafluoroethylene resin is prepared by copolymerization of tetrafluoroethylene, perfluoropropyl vinyl ether and functionalized fullerene, and the mass ratio of the tetrafluoroethylene, the perfluoropropyl vinyl ether and the functionalized fullerene is (95.0-98.5): 0.1-1.0): 1.0-5.0.
  3. 3. The modified polytetrafluoroethylene material for electrolytic cells according to claim 1, wherein said polyimide resin has a glass transition temperature Tg of not less than 250 ℃.
  4. 4. The modified polytetrafluoroethylene material for electrolytic cells according to claim 1 wherein said fluorinated ceramic microspheres are at least one of fluorinated alumina microspheres, fluorinated silica microspheres or fluorinated boron nitride microspheres having a particle size in the range of 5-50 μm.
  5. 5. The modified polytetrafluoroethylene material for electrolytic cells according to claim 2, wherein said method for producing functionalized fullerenes comprises the steps of: a) Fullerene oxidation, namely dispersing the fullerene in a concentrated acid mixed solution, carrying out oxidation treatment for 0.5-4 hours at 60-90 ℃, separating, washing and drying after the treatment to obtain the fullerene with carboxylated surface; b) Dispersing the carboxylated fullerene obtained in the step a) in a first organic solvent, and reacting with thionyl chloride or oxalyl chloride under a catalytic condition to obtain a fullerene intermediate with the surface rich in acyl chloride groups; c) And b) functional group grafting, namely dispersing the fullerene intermediate with the surface rich in acyl chloride groups obtained in the step b) in a second organic solvent, reacting with an amine compound or an alcohol compound, separating a product after the reaction is finished, washing and drying to obtain the functional fullerene with the surface grafted with amino or hydroxyl.
  6. 6. The modified polytetrafluoroethylene material for electrolytic cells according to claim 5 wherein said amine compound is selected from the group consisting of ethylenediamine, hexamethylenediamine and primary amino group-containing silane coupling agents, and said alcohol compound is selected from the group consisting of ethylene glycol, glycerol and hydroxyl group-containing silane coupling agents.
  7. 7. The modified polytetrafluoroethylene material for electrolytic cells according to claim 5 wherein said first organic solvent is at least one of methylene chloride, 1, 2-dichloroethane, tetrahydrofuran, toluene, and said second organic solvent is at least one of methylene chloride, tetrahydrofuran, toluene.
  8. 8. The method for producing a modified polytetrafluoroethylene material for electrolytic cells according to any one of claims 1 to 7, comprising the steps of: (1) Adding deionized water, a fluorine-containing dispersing agent, functionalized fullerene and part of perfluoropropyl vinyl ether into a polymerization reactor, premixing, carrying out ultrasonic treatment for 15-30min, then introducing tetrafluoroethylene and the rest of perfluoropropyl vinyl ether for mixing, and carrying out copolymerization under the action of an initiator at 50-80 ℃ and under the pressure of 1.0-3.0MPa to obtain the modified polytetrafluoroethylene resin; (2) Weighing the components according to the proportion, and mixing the modified polytetrafluoroethylene resin, polyimide resin, fluorinated ceramic microspheres and fluorinated graphene in a high-speed mixer according to the proportion to form uniform composite powder; (3) Pressing the composite powder in the step (2) into a green body, then sintering the green body step by step under the protection of inert atmosphere, firstly heating to 320-340 ℃ and preserving heat, then continuously heating to 365-380 ℃ and preserving heat, and finally cooling to room temperature by a program to obtain the modified polytetrafluoroethylene material for the electrolytic tank.
  9. 9. The method for preparing a modified polytetrafluoroethylene material for an electrolytic tank according to claim 8, wherein the step-by-step sintering in the step (3) is specifically performed by heating to 320-340 ℃ at 20-50 ℃ per hour, maintaining for 1-4 hours, then heating to 365-380 ℃ at 20-40 ℃ per hour, maintaining for 2-8 hours, and then cooling to room temperature at 20-50 ℃ per hour.
  10. 10. The method for producing a modified polytetrafluoroethylene material for electrolytic cells according to claim 8, wherein said high-speed mixing in step (2) is performed in a high-speed mixer for a mixing time of 25 to 75 minutes at a rotational speed of 1000 to 3000rpm.

Description

Modified polytetrafluoroethylene material for electrolytic tank and preparation method thereof Technical Field The invention relates to the technical field of polymer composite materials, in particular to a modified polytetrafluoroethylene material for an electrolytic tank and a preparation method thereof. Background Electrolytic water hydrogen production, particularly alkaline water electrolysis and PEM water electrolysis, is currently the dominant technology for obtaining "green hydrogen". The sealing reliability of the long-term operation of the electrolytic tank as core equipment is directly related to hydrogen production efficiency, safety and operation cost. The sealing gasket is a key component for ensuring that the electrolytic tank does not leak mediums (such as alkali liquor, high-purity water, hydrogen and oxygen). The conditions inside the electrolyzer are extreme and generally have challenges of high temperature (60-90 ℃), high pressure (1-3 MPa or even higher), highly corrosive media (such as 30% koh solution or acidic PEM environment), continuous tightening stress, and hydrogen permeation. This places extremely high demands on the overall properties of the sealing material, that it must have excellent long-term creep relaxation resistance to maintain seal specific pressure, excellent chemical resistance to resist medium attack, good compression set resilience to compensate for thermal cycling and stress fluctuations, and extremely low gas permeability to ensure safety. Polytetrafluoroethylene (PTFE) is widely used to prepare sealing materials due to its excellent chemical inertness, temperature resistance and low coefficient of friction. However, pure PTFE has the obvious defects of poor creep resistance (commonly known as cold fluidity), poor sealing failure caused by plastic deformation under long-term stress, low hardness, insufficient rebound resilience and poor thermal conductivity. These drawbacks limit their use in high-end, long-life electrolysis cells. To improve the performance of PTFE, a fill modification process is typically employed. Common fillers include glass fibers, carbon fibers, graphite, molybdenum disulfide, bronze powder, and the like. These modifications improve the mechanical strength or lubricity of PTFE to some extent, but tend to sacrifice other properties when improving certain properties, for example, the incorporation of inorganic fillers may reduce the corrosion uniformity or increase brittleness of the material, and have limited effect on inhibiting the inherent slip (creep) of the PTFE molecular chain. In addition, the conventional physical blending is difficult to solve the problem of weak interface combination of the filler and the PTFE matrix, and the interface is easy to become a failure source in a long-term corrosion environment. In recent years, nanomaterials and organic high performance polymers have been studied intensively as PTFE reinforcement phases. The carbon nano tube can improve strength and heat conductivity, but is easy to agglomerate, the graphene can enhance barrier property, but is easy to stack between sheets, and the polyimide resin can obviously improve temperature resistance and mechanical strength. However, how to combine these reinforcing phases with the PTFE matrix efficiently and firmly and cooperatively solve the comprehensive demands of creep resistance, corrosion resistance, high sealing and the like remains a technical difficulty. Meanwhile, from the aspect of molecular design, the intrinsic creep resistance of the PTFE chain structure is improved by copolymerization and modified, and chemical bonding is generated between the PTFE chain structure and a nano reinforcing phase, so that the PTFE chain structure is an effective way for obtaining breakthrough performance, but related researches and application in electrolytic tank sealing materials are insufficient. Therefore, the sealing material with long service life, which has excellent creep relaxation resistance, high strength, excellent chemical corrosion resistance and extremely low permeability, is specially suitable for severe electrolytic tank working conditions, and has important industrial application value. Disclosure of Invention The invention aims to: The invention aims to provide a long-life sealing material which has excellent creep relaxation resistance, high strength, excellent chemical corrosion resistance and extremely low permeability and is specially suitable for severe electrolytic tank working conditions, and a preparation method thereof. The technical scheme of the invention is as follows: The modified polytetrafluoroethylene material for the electrolytic tank comprises, by weight, 100-120 parts of modified polytetrafluoroethylene resin, 5-15 parts of polyimide resin, 3-8 parts of fluorinated ceramic microspheres and 0.5-5 parts of fluorinated graphene. Further, the modified polytetrafluoroethylene resin is prepared by copolymerization of tetrafluoroethyle