Pure PTFE has outstanding excellent comprehensive properties, high temperature resistance, corrosion resistance, non-stick, self-lubrication, excellent dielectric properties, and low coefficient of friction. It is mainly used as engineering plastics. The following is the production method and application of pure PTFE.
Production method of pure PTFE
The critical pressure of pure PTFE material is about 27.5 MPa. The compressive strength of PTFE material decreases with the increase of compression pressure; the compression modulus increases with the increase of the compression pressure. Finally, the forming pressure of PTFE was determined to be 27.5 MPa. The determined sintering process is: sintering temperature of 380 ° C, holding time of 4h, heating rate of 80 ° C / h at 200 ° C, 60 ° C / h above 200 ° C, and the cooling rate is cooling with the furnace. It also has very good electrical properties, and its electrical insulation is not affected by temperature.
1. Preparation of monomer tetrafluoroethylene Industrially, trichloromethane is used as raw material, trichloromethane is fluorinated with anhydrous hydrofluoric acid, the reaction temperature is above 65 ° C, antimony pentachloride is used as a catalyst, and finally thermal cracking is used. Tetrafluoroethylene is produced by the method; (Tetrafluoroethylene can also be produced by the reaction of zinc with tetrafluorodichloroethane at high temperature.)
2. Preparation of pure PTFE: In an enamel or stainless steel polymerization kettle, water is used as the medium, potassium persulfate is used as the initiator, ammonium perfluorocarboxylic acid is used as the dispersant, fluorocarbon compounds are used as the stabilizer, and tetrafluoroethylene is subjected to oxidation reduction. Polymerization to obtain pure PTFE. Various auxiliaries are added to the reaction kettle, the tetrafluoroethylene monomer enters the polymerization kettle in the gas phase, the temperature in the kettle is adjusted to 25 ° C, and then a certain amount of activator (sodium metabisulfite) is added, and the polymerization is initiated by oxidation and reduction system. During the polymerization process, monomers were continuously added to maintain the polymerization pressure of 0.49 to 0.78 MPa. The dispersion obtained after the polymerization was diluted with water to a certain concentration, and the temperature was adjusted to 15 to 20 ° C. After being coagulated with mechanical stirring, it was washed with water and dried. This product is obtained as a fine granular resin.
Application of pure PTFE
Pure PTFE can be formed by compression or extrusion; it can also be made into an aqueous dispersion for coating, impregnation or fiber. Pure PTFE is widely used in industries such as atomic energy, national defense, aerospace, electronics, electrical, chemical, machinery, instruments, meters, construction, textile, metal surface treatment, pharmaceutical, medical, textile, food, metallurgy and smelting. Corrosive materials, insulating materials, anti-stick coatings, etc. make it an irreplaceable product.
The above is an introduction to the production method and application of pure PTFE. I hope that everyone will be helpful after understanding the production method and application of pure PTFE.