PTFE film extrusion production process

Teflon film extrusion production process

PTFE film is used in the manufacture of electromechanical and electronic industries for advanced electrical insulation liner, sheathing, abrasion reduction materials, chemical anticorrosion materials and wire and cable insulation layer. It has excellent dielectric properties, non-aging, good corrosion performance and a wide range of strength. The film is undirected film, undirected film is developed into directional and semi-directional film by pressing.

　　The production process of PTFE film includes several steps of mixing, embryo making, extrusion, calendering, longitudinal stretching, transverse stretching and shaping. Extrusion of PTFE films is one of the processing methods, which is essentially a synthesis of conventional extrusion and calendering methods, except that in the processing, the resin is not melted and plasticized, but is processed in raw material. Extrusion production method of PTFE film is the use of PTFE PTFE under the action of compression force, can produce residual deformation characteristics, adding certain additives, residual deformation can also be increased.

This method is to add extrusion aid PTFE material pressed into a certain density of the type of blank, put into the extruder appropriate heating, extrusion of thin strips, and then sent to the calendering roller calendering into film, and then remove the extrusion aid can be.

　　Extrusion production of PTFE film is suitable for good dispersion of the powder with appropriate extrusion aid. The extrusion aid can increase the lubrication of PTFE molecules and reduce the resistance of pushing and squeezing. Commonly used extrusion aid for paraffin oil, the amount of 17 ~ 20%. In recent years, also developed dichloroethylene, etc.

　　The pre-pressed bar is generally cylindrical in shape and is pressed into shape in a hydraulic press. Depending on the height of 68.6~147Pa pressure is used respectively, so that the compression ratio of 50~150 can be achieved. Pushing and extruding the material bar is done in the pushing and extruding machine. In order to physiological, pushing extrusion should be carried out in the pre-pressing billet preheating to about 200℃, the pushing pressure is 490~980Pa, and the fine material strip of 0.5~1cm in diameter can be obtained.

　　Fine material strips in the calendering before the general to preheat in the water tank to 40 ~ 60 ℃ into the calender, calendering roller temperature is generally 50 ~ 80 ℃, calendering roller speed is generally 3 ~ 10m / min, calendering speed is generally much greater than the speed of pushing out the material. Therefore, in order to improve the production efficiency, several pusher machines should feed one calender.

　　In order to prevent the calendering film from producing wavy edges, the fishtail-shaped guide plate should be designed according to the stretching form of the calendering film. Depending on the needs, the extruded film is subjected to different post-treatment. If the film is required to have a very low content of extrusion aids, it should be extracted and dried at 150-200°C after treatment. If the film is allowed to contain a certain amount of auxiliaries, extraction is not necessary, but drying at different temperatures is required. The higher the drying temperature, the lower the content of auxiliary extrusion. Generally high temperature up to 400 ℃. Cold extrusion processing film is actually a raw material film, but the performance of this film is basically comparable to the cooked film, with high elongation and tensile strength, but not as good as the turned film.