Sheets for blister packaging are called hard films or films. Commonly used are PET (polyethylene terephthalate) hard films, PVC (polyvinyl chloride) hard films, and PS (polystyrene) hard films. PS hard film has low density, poor toughness, easy to burn, and styrene gas (belonging to harmful gas) will be generated during burning, so it is generally used to produce plastic trays for various industries. PVC hard film has moderate toughness and is not easy to burn. Chlorine gas will be generated during combustion, which will have certain impact on the environment. PVC is easy to heat seal. It can be sealed with a sealing machine and a high-frequency machine. It is the main raw material for producing transparent plastic products.
PET hard film has good toughness, high transparency, easy to burn, and does not produce harmful gases during combustion. It is an environmentally friendly material, but the price is high. It is suitable for high-end plastic products. Blister shells in European and American countries generally require PET hard film, but It is not easy to heat seal, which brings great difficulties to packaging. In order to solve this problem, people use a material called PETG ethylene glycol modified-polyethylene terephthalate. Heat sealability, PET also has high environmental protection and transparency, but the price is higher.