Blistering is a plastic processing technology that involves heating flat plastic sheets to soften them, then vacuum adsorbing them onto the surface of a mold, cooling them, and forming them. It is widely used in industries such as plastic packaging, lighting, advertising, and decoration. And vacuum formed paper packaging uses paper plastic composite products instead of plastic sheets for vacuum formed packaging.
The sheets used for vacuum packaging are called hard sheets or films, and commonly used ones include PET (polyethylene terephthalate) hard sheets, PVC (polyvinyl chloride) hard sheets, and PS (polystyrene) hard sheets. PS hard sheet has low density, poor toughness, and is easy to burn. When burned, it produces styrene gas (a harmful gas), so it is generally used to produce various industrial vacuum formed trays.
PVC hard sheets have moderate toughness and are not easy to burn. When burned, they produce chlorine gas, which has a certain impact on the environment. PVC is easy to heat seal and can be sealed with sealing machines and high-frequency machines. It is the main raw material for producing transparent vacuum formed packaging box products.
PET hard sheets have good toughness, high transparency, and are easy to burn. They do not produce harmful gases when burned, making them environmentally friendly materials. However, they are expensive and suitable for high-end vacuum formed products. In European and American countries, PET hard sheets are generally required for vacuum formed shells, but they are not easy to heat seal, which brings great difficulties to packaging. To solve this problem, people use a material called PETG ethylene glycol modified polyethylene terephthalate. This material has both the heat sealing properties of PVC and the high environmental friendliness and transparency of PET, but the price is higher.
