Plastic sheets for plastic packaging are called hard pieces or films, commonly used: PET (Polyterephthalate two ester) hard slices, PVC (polyvinyl chloride) hard slices, and PS (polystyrene) hard slices.

PS is low density, poor toughness, easy to burn, when burning, it will produce styrene gas (a harmful gas), so it is generally used to produce a variety of industrial plastic tray.

PVC hard piece toughness is moderate, it is not easy to burn. It will produce chlorine gas when burning. It has a certain influence on the environment. PVC is easy to heat in. It can be sealed by a sealing machine and high frequency machine. It is the main raw material for producing transparent plastic products.

PET has good toughness, high transparency, easy combustion and no harmful gas when burning. It is an environmentally friendly material, but the price is high. It is suitable for high grade plastic products. The blister shell in European and American countries usually requires PET hard film, but it is not easy to heat, and it is difficult to package. In order to solve this problem, people adopt the problem. A material called PETG ethylene glycol modified poly (ethylene terephthalate) glycol, which has both the susceptibility to PVC and the high environmental and transparency of PET, but a higher price.