Valve Sealing is a necessary general technology in various industrial fields. Not only construction, petrochemical, shipping, machinery manufacturing, energy, transportation, environmental protection and other industries can not be separated from the sealing technology, aviation, aerospace and other cutting-edge industries are also closely related to sealing technology. Valve sealing is used in a wide range of fields. Where fluid storage, transport, energy conversion devices are involved in sealing problems.

With the development of science and technology, the working conditions of valve sealing structure are more stringent. As the temperature, pressure and corrosivity of the valve sealing fluid have increased significantly, traditional sealing materials such as felt, hemp, asbestos, putty, etc. can no longer meet the requirements of the valve, and are gradually replaced by rubber and other synthetic materials.

At present, all kinds of sealing products with different shapes and specifications are produced and manufactured from polymer materials, but still mainly from synthetic rubber. Because most of the working conditions that require sealing are working in harsh and demanding environments, such as the requirements of oil resistance, chemical medium corrosion resistance, high and low temperature resistance, weather resistance, and harmful gas resistance, etc. Synthetic rubber with different characteristics must be selected according to different working conditions.

Synthetic materials such as rubber are generally macromolecular polymers, and functional groups with different characteristics (such as chlorine, fluorine, cyano, vinyl, isocyanate, hydroxyl, carboxyl, alkoxy, etc.) in the macromolecular chain become active crosslinking points. Under the action of catalyst, vulcanizing agent, or high temperature and high energy radiation, the macromolecules are transformed from a linear, branched structure into a spatially networked structure, a process known as vulcanisation. After vulcanisation of rubber or other synthetic materials, the macromolecules lose their original fluidity and are called elastomers with high elastic deformation. Commonly used rubber and synthetic materials for valve sealing include NBR, Si (VMQ), FKM (Viton), EPDM, PU, PTFE, etc.