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CN-121975254-A - Polytetrafluoroethylene composite material and preparation method thereof

CN121975254ACN 121975254 ACN121975254 ACN 121975254ACN-121975254-A

Abstract

The invention belongs to the technical field of preparation of polymer composite materials, and in particular relates to a polytetrafluoroethylene composite material and a preparation method thereof, wherein the preparation method comprises the steps of S1, preprocessing a reinforcing phase, namely S11, mixing potassium magnesium titanate whisker and potassium titanate whisker, adding an ethanol solution of a silane coupling agent, mixing and drying to obtain modified double whisker; S12, adding nano montmorillonite into deionized water, performing ultrasonic dispersion, adding a cationic surfactant, stirring, performing centrifugal separation, and drying to obtain organic modified nano montmorillonite, S13, soaking short carbon fibers into a nitric acid solution, refluxing, washing to be neutral, and drying to obtain surface hydroxylated short carbon fibers, S2, preparing a composite emulsion, namely adding deionized water into a reaction kettle, sequentially adding the materials, stirring to match with ultrasonic dispersion to form uniform reinforced phase dispersion, then adding a surfactant and an initiator, stirring, S3, performing polymerization reaction, and S4, performing post-treatment.

Inventors

  • MA YUANHAO
  • LI WANGJIA
  • XIE YANG
  • SU JUNJIE
  • LAN FUYING

Assignees

  • 江西固康新材料有限公司

Dates

Publication Date
20260505
Application Date
20260202

Claims (10)

  1. 1. The preparation method of the polytetrafluoroethylene composite material is characterized by comprising the following steps of: S1, modifying potassium magnesium titanate whisker and potassium titanate whisker through a silane coupling agent to obtain modified double whisker, and modifying nano montmorillonite through a cationic surfactant to obtain organic modified nano montmorillonite; s2, adding deionized water into a reaction kettle, sequentially adding the modified double whiskers, the organic modified nano montmorillonite and the surface hydroxylated short carbon fibers, stirring and performing ultrasonic dispersion to form a reinforcing phase dispersion liquid; s3, sealing the reaction kettle, and introducing tetrafluoroethylene monomer to perform polymerization reaction; s4, cooling the reaction kettle to room temperature, adding an aluminum sulfate solution for demulsification, stirring, centrifugally separating, collecting precipitate, repeatedly washing the precipitate, and drying in vacuum to obtain the polytetrafluoroethylene composite material.
  2. 2. The method for preparing a polytetrafluoroethylene composite according to claim 1, wherein S1 comprises: S11, mixing potassium magnesium titanate whiskers and potassium titanate whiskers, adding an ethanol solution of a silane coupling agent, mixing, and drying to obtain modified double whiskers; s12, adding nano montmorillonite into deionized water, performing ultrasonic dispersion, adding a cationic surfactant, stirring, performing centrifugal separation, and drying to obtain organic modified nano montmorillonite; s13, soaking the short carbon fibers in a nitric acid solution, refluxing, washing to be neutral and drying to obtain the surface hydroxylation short carbon fibers.
  3. 3. The method for producing a polytetrafluoroethylene composite according to claim 2, wherein in step S11: The length of the potassium magnesium titanate whisker is between 5 and 20 mu m, and the diameter is between 0.1 and 0.5 mu m; The molecular formula of the potassium titanate is K 2 Ti 6 O 13 , the size of the potassium titanate whisker is 3-15 mu m in length and 0.1-0.3 mu m in diameter, and the mass ratio of the potassium magnesium titanate whisker to the potassium titanate whisker is 1:1; The silane coupling agent is KH-550, the volume fraction of ethanol in the ethanol solution of the silane coupling agent is 70-80%, and the mass of the silane coupling agent is 1-3% of the sum of the mass of the potassium magnesium titanate whisker and the potassium titanate whisker; the mixing after adding the ethanol solution of the silane coupling agent is stirring for 1-2h at 60-80 ℃; the drying is carried out at 100-120 ℃ for 2-3h.
  4. 4. The method for producing a polytetrafluoroethylene composite according to claim 2, wherein in step S12: The grain diameter of the nano montmorillonite is between 20 and 100 nm; the ultrasonic dispersion time is 30-60min, and the ultrasonic dispersion power is 300-500W; The cationic surfactant is cetyl trimethyl ammonium bromide, and the mass of the cationic surfactant is 13-15% of the mass of the nano montmorillonite; The stirring is carried out at 50-70 ℃ for 1-1.5h; the drying is carried out at 90-110 ℃ for 1.5-2.5h.
  5. 5. The method for producing a polytetrafluoroethylene composite according to claim 2, wherein in step S13: the short carbon fibers have the dimensions of 50-200 mu m in length and 5-10 mu m in diameter; the concentration of the nitric acid is 5-10% based on mass concentration; The reflux is carried out at 80-90 ℃ for 2-3 hours; the drying is carried out at 110-130 ℃ for 3-4 hours.
  6. 6. The method for preparing a polytetrafluoroethylene composite according to claim 1, wherein in step S2: the addition amount of the modified double whiskers accounts for 5-10% of the mass of the final polytetrafluoroethylene composite material; the addition amount of the organic modified nano montmorillonite accounts for 3-8% of the mass of the final polytetrafluoroethylene composite material; The addition amount of the surface hydroxylation short carbon fiber accounts for 2-5% of the mass of the final polytetrafluoroethylene composite material; The stirring and ultrasonic dispersion are carried out synchronously with mechanical stirring, the ultrasonic dispersion is in an intermittent working mode of suspending for 10s every 30s, the stirring rotating speed is 200-300r/min, the dispersing power of the ultrasonic dispersion is 400-600W, and the stirring is matched with the ultrasonic dispersion for 40-80min; The environment-friendly fluorine-containing surfactant is potassium perfluorobutyl sulfonate accounting for 1-3% of the mass of tetrafluoroethylene monomer, the addition amount of the ammonium persulfate initiator accounts for 0.05-0.1% of the mass of tetrafluoroethylene monomer, and the environment-friendly fluorine-containing surfactant and the ammonium persulfate initiator are added and then stirred for 15-30min.
  7. 7. The method for preparing the polytetrafluoroethylene composite material according to claim 1, wherein the specific method of step S3 is as follows: Sealing the reaction kettle, vacuumizing to-0.08 to-0.09 MPa, introducing tetrafluoroethylene monomer at the speed of 0.1-0.3L/min, raising the pressure in the kettle to 0.8-1.2MPa, raising the temperature to 50-70 ℃, carrying out heat preservation and polymerization for 3-6h, controlling the temperature fluctuation to be less than or equal to 3 ℃ through jacket cooling water during the process, stopping introducing tetrafluoroethylene monomer when the pressure in the kettle is reduced to 40-60% of the initial pressure, and stopping the reaction.
  8. 8. The method for preparing polytetrafluoroethylene composite according to claim 1, wherein in step S4: The addition amount of the aluminum sulfate solution is 2-8% of that of tetrafluoroethylene monomer, stirring is carried out for 30-45min after the aluminum sulfate solution is added, the rotation speed of centrifugal separation is 4000-6000r/min, the centrifugal separation time is 10-15min, the repeated washing is to wash the precipitate with deionized water until the pH value of the washing solution is=6.5-7.5, the vacuum drying is carried out for 5-8h at 100-120 ℃, and the concentration of the aluminum sulfate solution is 8-10%.
  9. 9. The method for preparing the polytetrafluoroethylene composite material according to claim 1, wherein in the step S4, the vacuum degree of vacuum drying is-0.09 to-0.095 MPa, and the water content of the polytetrafluoroethylene composite material powder is ensured to be less than or equal to 0.5%.
  10. 10. A polytetrafluoroethylene composite material, characterized in that it is obtained by the preparation method according to any one of claims 1 to 9, comprising modified double whiskers, organically modified nano montmorillonite, surface-hydroxylated short carbon fibers; The modified double whiskers are potassium magnesium titanate whiskers and potassium titanate whiskers modified by a silane coupling agent, and the mass content of the modified double whiskers in the polytetrafluoroethylene composite material is 5-10%; The organic modified nano montmorillonite is cationic surfactant intercalated nano montmorillonite, and the mass content of the organic modified nano montmorillonite in the polytetrafluoroethylene composite material is 2-5%; the mass content of the surface hydroxylation short carbon fiber in the polytetrafluoroethylene composite material is 2-5%.

Description

Polytetrafluoroethylene composite material and preparation method thereof Technical Field The invention belongs to the technical field of preparation of polymer composite materials, and particularly relates to a polytetrafluoroethylene composite material and a preparation method thereof. Background Polytetrafluoroethylene (PTFE) is widely used in sealing, lubrication, electronics and other fields due to its excellent corrosion resistance, high temperature resistance and low friction coefficient, but pure PTFE has the disadvantages of low mechanical strength, poor wear resistance, obvious cold flow and the like, which limits its application under high-end working conditions. In the prior art, PTFE performance is often improved by adding a single reinforcing phase (such as carbon fiber, montmorillonite and titanate whisker), but the single reinforcing phase is difficult to meet the requirement of multiple performances, for example, the carbon fiber can improve strength and easily cause the increase of friction coefficient of a composite material, the montmorillonite can optimize wear resistance and has limited improvement on tensile property, and the titanate whisker can enhance high temperature resistance and is not uniformly dispersed and easily agglomerated. In addition, most of traditional PTFE has micron-sized particle size, and has weak bonding force with the enhanced interphase interface, thereby further restricting the improvement of the performance of the composite material. Disclosure of Invention The invention aims to provide a polytetrafluoroethylene composite material and a preparation method thereof, wherein the reinforced phase is pretreated by a preparation process, and emulsion polymerization is adopted to synchronously realize nano polytetrafluoroethylene preparation and reinforced phase dispersion so as to remarkably improve the comprehensive performance of the composite material. The technical scheme of the invention is that the invention provides a preparation method of a polytetrafluoroethylene composite material, which comprises the following steps: S1, modifying potassium magnesium titanate whisker and potassium titanate whisker through a silane coupling agent to obtain modified double whisker, and modifying nano montmorillonite through a cationic surfactant to obtain organic modified nano montmorillonite; s2, adding deionized water into a reaction kettle, sequentially adding the modified double whiskers, the organic modified nano montmorillonite and the surface hydroxylated short carbon fibers, stirring and performing ultrasonic dispersion to form a reinforcing phase dispersion liquid; s3, sealing the reaction kettle, and introducing tetrafluoroethylene monomer to perform polymerization reaction; s4, cooling the reaction kettle to room temperature, adding an aluminum sulfate solution for demulsification, stirring, centrifugally separating, collecting precipitate, repeatedly washing the precipitate, and drying in vacuum to obtain the polytetrafluoroethylene composite material. Further, the step S1 includes: S11, mixing potassium magnesium titanate whiskers and potassium titanate whiskers, adding an ethanol solution of a silane coupling agent, mixing, and drying to obtain modified double whiskers; s12, adding nano montmorillonite into deionized water, performing ultrasonic dispersion, adding a cationic surfactant, stirring, performing centrifugal separation, and drying to obtain organic modified nano montmorillonite; s13, soaking the short carbon fibers in a nitric acid solution, refluxing, washing to be neutral and drying to obtain the surface hydroxylation short carbon fibers. Further, in the step S11, the length of the potassium magnesium titanate whisker is between 5 and 20 mu m, the diameter is between 0.1 and 0.5 mu m, the molecular formula of the potassium titanate whisker is K 2Ti6O13, the size of the potassium titanate whisker is between 3 and 15 mu m, the diameter is between 0.1 and 0.3 mu m, the mass ratio of the potassium magnesium titanate whisker to the potassium titanate whisker is 1:1, the silane coupling agent is KH-550, the volume fraction of ethanol in an ethanol solution of the silane coupling agent is between 70 and 80%, the mass of the silane coupling agent is 1 to 3% of the sum of the mass of the potassium magnesium titanate whisker and the potassium titanate whisker, the mixture after the addition of the ethanol solution of the silane coupling agent is stirred for 1 to 2 hours at the temperature of between 60 and 80 ℃, and the drying is carried out for 2 to 3 hours at the temperature of between 100 and 120 ℃. Further, in the step S12, the particle size of the nano montmorillonite is 20-100nm, the ultrasonic dispersion time is 30-60min, the ultrasonic dispersion power is 300-500W, the cationic surfactant is cetyl trimethyl ammonium bromide, the mass of the cationic surfactant is 13-15% of that of the nano montmorillonite, the stirring is carried out at 50-70 ℃ for