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Secondary processing Technology of Fluoroplastics
- Jun 17, 2018 -

   

     Due to the processing characteristics of fluorine plastics, some products are difficult to form in one time, and the usable finished products must be processed twice. Secondary processing technology has: cutting, welding, lining, blowing and so on.


     Cutting: similar to metal cutting, equipment such as lathe, drilling machine, planer, etc. Note that the blank must be placed 24 hours before cutting.


     Welding: hot pressing welding and hot air welding rod welding two kinds. Hot pressing welding, must be in the special forceps, heating to 327 ℃, at the same time can be welded under pressure. The hot air welding rod is a PFA bar, which is heated and pressurized through the PFA to connect the two pieces together.


     Lining: polytetrafluoroethylene and perfluoroethylenepropylene (F4 and F46) plastic lined with black metal pipes and pipe fittings, which can be used in chemical anticorrosive and corrosion resistant materials.


     Bloating: the products are bellows and heat shrink tubes, heat shrink film and so on. It is also divided into continuous blow-up and intermittent blow-up.

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     For example, the tube billet of F46 heat shrinkage tube is prepared by water cooling vacuum setting method. The tube drawing ratio is 3-7, the length of melting cone is controlled at 10 ~ 20 mm, the blowing mold temperature is 80-160 ℃, the swelling pressure is 0. 1-0. 2 MPA, the traction linear velocity is 80-500 mm / min. Other blow-up F 4 spiral tube. Such as soft belt of PTFE machine guide rail: PTFE fine grain material is suspended, after crushing, after 20 mesh sieve, the particle size of bronze powder or aluminum powder is 200 mesh, for 100mm high blank, the pressure is kept for 5 minutes, the air is released three times in the middle, the heating rate is 50-60 ℃ / hour during sintering, Heat preservation at 320 ℃ for 1 hour, cooling to 150 ℃ out of the oven. Blanks before turning, should be preheated to 80 ℃, heat preservation for an hour before proceeding. Soft tape should be treated with sodium naphthalene, including naphthalene 51 g, tetrahydrofuran 100 ml, metal sodium proper amount, thickness less than 1 mm in sodium naphthalene treatment solution for 1-3 minutes, and then washed with hot water at 90 ℃.


     For example, PTFE can be mixed with polybenzene, polyimide, polyhydroxybenzoate, and also filled with graphite, molybdenum disulfide, bronze powder, etc. It can be used in hydraulic gate, fluoroplastic 46 can be used in corrosion resistant ball valve, its moulding temperature is 320-350 ℃, Molding pressure 3-30 MPA, setting temperature 120-150 ℃.


     The glass fiber reinforced PTFE pipe as the inner lining of the pipe can solve the corrosion problem of the pipe. The technological process is as follows: PTFE resin is mashed and sieve, but pressure forming is sintered and shaped. Outside circular turning test; surface activation treatment; FRP flange pack flange; curable flange head turning; demandrel rod assembly Gasket flanging finished product such as PVDF sealing ring: add 1 phr of acid absorbent, Mixing ball milling for 24 hours, in the press of the template temperature of 195-250 ℃, slowly pressurizing to 2.5-3.5 MPA, releasing air 1-2 times, rapidly moving to 180-190 ℃ when the mold temperature rises to 180-190 ℃, moving quickly to the cold press when cooling at 14 MPA and cooling at 50 ℃, and trimming the edge, Put into 130 ℃ oven, heat treatment for 24 hours, you can inspect the packaging. Fluorinated plastics have developed into fluorinated epoxy resins (for optical communication systems, perfluoroelastomers (for semi-conductive equipment), thermoplastic fluoroelastomers (for medical treatment, cable coating, perfluoropolyether) (for high and low temperature resistance grease). There is also polyfluoroethylene solvent-free processing. Only 9 phr lubricant and 4 phr heat stabilizer and 2 phr other auxiliaries can be added to the molding process.

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