1.Usage: the usage in the market of PVC, recent years the main effort is to open widely the usage in building materials .in the world developed countries 65% of the PVC is used in building materials(used mainly in pipe materials ),other packing materialsand electrical equipment. The series of advantages of PVC products such as light quality,corrosion-resisting,save the energy and be difficult to burn,make its rapid development in the building industry.