PVC can be divided into soft PVC and hard PVC. The hard PVC for about two-thirds of the market, soft PVC accounted for a third. Soft PVC are used for floor, ceiling and leather surface, but as a result of soft PVC contains softening agent (this is also soft PVC and hard PVC difference), easy to become fragile, is not easy to preserve, so its use range was limited. Hard PVC contains no softening agent, so good suppleness, easy molding, not easy to be brittle, non-toxic pollution-free, save for a long time, so there are a lot of development and application value. The essence of the PVC is a kind of vacuum suction plastic film, used in the various types of panel surface packaging, so they are called decoration film, with film, used in building materials, packaging, medicine, and many other industries. The building materials industry accounted for the largest proportion, at 60%, followed by packaging industry, and many other small range application industry. Polyvinyl chloride (PVC) molecules containing chlorine atom. Because C - CL key dipole influence, it is a kind of polarity strong material. PVC has the very good acid and alkali resistance, wear resistance, fire resistance and insulation performance, but light, heat stability is poor. Business, preparation of PVC have four methods: suspension method, ontology method, emulsion method and solution method. The most common suspension method, most applications of PVC resin is this kind of resin. The product contains according to the amount of plasticizer (typically dibutyl phthalate, dioctyl phthalate) is divided into hard, half hard and soft three kinds of materials. Rigid PVC including plasticizer for 10-25%, half hard PVC for 30 ~ 40%, soft PVC for forty to 70%. All PVC products must contain a certain amount of stabilizing agent, in order to avoid degradation occurred in machining process. Soft PVC products of the plasticizer is to make polymer become soft. Plasticizer choice or plasticizer of combination, and finally the finished expected performance to decide. Most of the plasticizer to some extent also plays the role of processing aid. Plasticizer reduced resin melt temperature and viscosity, which can prevent resin adhesive to processing equipment on the metal parts
