Polyvinyl chloride used to be the most used plastic in history, but now it is replaced by polyethylene and PET in some fields, but it is still widely used, and its consumption is second only to polyethylene and polypropylene. There are many forms of PVC products, which can be divided into three categories: hard PVC, soft PVC and PVC paste. Rigid PVC is mainly used for extruded products such as pipes, door and window profiles and sheets, as well as injection-molded parts and bottle products such as pipe joints and electrical parts by extrusion blow molding, accounting for more than 65% of PVC consumption. Soft PVC is mainly used in calendered sheets, automobile interior accessories, handbags, films, labels, wires and cables, medical supplies and so on. PVC paste accounts for about 10% of PVC products, and the main products are plastic-lined products.
Polyvinyl chloride (PVC) is also a common plastic. It is a resin composed of PVC resin, plasticizer and antioxidant, and it is not toxic in itself. However, the main auxiliary materials such as plasticizers and antioxidants are toxic. The plasticizers used in daily-use PVC plastics mainly include dibutyl terephthalate and dioctyl phthalate. These chemicals are toxic, and so is lead stearate, an antioxidant of PVC. When PVC products containing lead salt antioxidants come into contact with solvents such as ethanol and ether, lead will be precipitated. When PVC containing lead salt is used as food packaging, lead molecules will diffuse into oil when encountering fried dough sticks, fried cakes, fried fish, cooked meat products and cakes and snacks, so it is not possible to use PVC plastic bags to pack food, especially oily food.