The Special Way of Producing PTFE Film
Polytetrafluoroethylene (PTFE) film is widely and diversely applied to from the external protective layer of conduits and the insulating layer of electrical components to the adhesion-proof layer of frying pans. Ptfe film is not produced through blowing as people think or through casting in the process of which the film is produced through being paring from a cylindrical blank.
PTFE which belongs to the family of fluoride is featured by its strong homeothermy. The material serves as insulation materials, since it is by no means inflammable. Of all kinds of the solid plastic, PTFE boasts the lowest frictional coefficient. The endurable flexural strength of PTFE, it is obvious, overtakes the two other fluorides, namely fluorinated ethylene propylene (FEP) and polyfluoroalkoxy (PFA). PTFE, however, has its own drawbacks: its melt viscosity is still very high with its temperature above 327℃ and it is tremendously sensitive to gap. For this, the common ways of shaping such as squeezing, laminating and blowing are barely imposed on PTFE.
Unlike the way of producing polyethylene film, before transforming the white powder into thin and transparent Ptfe film, there is another procedure in which PTFE should be compressed into pre-shaped film in the room temperature and then the film should be heated until above the crystallization point, namely through being sintering above the melting point, so as to coagulate into insoluble agglomerate.
The heat generally should be about 380℃. According to the processing condition and the kind of the resulting crystal, the density of the PTFE blank will vary from 2.1 g/ml to 2.3g/m after being sintering. If it takes much time to cool down, the density will become high. In this case, the material will be bestowed with high crystallinity, strong rigidity and high-shaped stability. Sintered under the pressure, PTFE will have quite high density and strong rigidity and be devoid of pore which is the prerequisite of producing extremely thin film.
The above-mentioned sintering for pre-shaping being finished, the job of sparing film could be done. All the operating components which are used on the equipments for sparing are put together in one tannunciator, which is installed in the right engine base and can be freely rotated. And the thickness and the speed of sparing film are also set in the control panel in advance. When the thickness of film and the revolution of blank are set, the electronic controller will automatically determine the speed of teflon sheet.