The ideal gasket structure should be plastic on the surface and elastomer on the inner layer. The plastic outer layer ensures sealing and closes to each other and even fits together, while the inner layer allows to compensate for a little separation of the sealing surface and always maintain a certain size on the seal. The compressive stress of many composite gaskets is based on this idea or slightly modified, but the principle is the same.
For example, polytetrafluoroethylene (PTFE) has good plasticity, excellent chemical corrosion resistance and wide operating temperature range (-190~250℃), and is generally used for static sealing flat gaskets, but due to some reasons, the resilience is poor As well as the tendency of cold flow, the simple application is limited. The combined structure can overcome this drawback. On the one hand, it can protect the gasket from corrosion by fluid media or prevent food and pharmaceutical industry products from contacting pollution.
On the other hand, the problem of poor springback and cold flow caused by simply using PTFE is improved. The mechanical properties of polytetrafluoroethylene are relatively soft and have very low surface energy. Polytetrafluoroethylene (F4, PTFE) has a series of excellent performance properties: high temperature resistance - long-term use temperature of 200~260 degrees, low temperature resistance - at -100 degrees still soft; corrosion resistant - resistant to aqua regia and all organic solvents; weather resistant - better aging life in plastics.
High smoothness-has a smaller coefficient of friction in plastics, non-sticky-has a smaller surface tension in solid materials and does not adhere to any substances; non-toxic-has physiological inertness; excellent electrical properties, is an ideal Class C insulating material . PTFE materials are widely used in important departments such as national defense and military industry, atomic energy, petroleum, radio, electrical machinery, and chemical industry.