After the products are packaged, they are required to protect the products, prevent qualitative changes, and ensure quality. After printing, they must beautify the products, explain the products, and promote the products. Commodities have to go through packages, transportation, sales and other links in the entire circulation process. In each link, the packaging materials must have corresponding characteristics.

1. Protection performance. First, the packaging material must have a certain mechanical strength. Different products have different requirements for packaging materials. For example: food packaging materials must fully comply with food packaging hygiene standards. That is, the packaging material does not migrate toxic substances, and is non-toxic, odorless, and odor-free. In addition, it is necessary to clarify the nature of the contents. For moisture-proof packaging, vacuum packaging and inflatable packaging, it must have the function of blocking the penetration of water vapor and oxygen in the environment into the packaging bag and preventing the inert gas in the bag from escaping. The packaging of quick-frozen vegetables and frozen foods must have the ability to withstand low-temperature freezing. The packaging materials for microwave sterilization food packaging and making "cooking bags" are required to have the function of high temperature cooking without shrinkage and deformation. The packaging of oily foods is required to have the functions of air tightness, oil resistance and ultraviolet penetration resistance. For skin-pack packaging and shrink packaging, plastic film must have a certain shrink tension. The packaging of tea, tablets, biscuits and the like needs a high degree of moisture resistance, air tightness and shading to maintain its original taste. For packaging of fresh vegetables and fruits, if the packaging materials with moisture and gas barrier are also used, it will bring side effects, because vegetables and fruits need a proper amount of oxygen to keep them fresh.

2. Operation performance. For plastic packaging printing materials, first of all, there must be printability, or after pretreatment can solve the problem of printing fastness. It also requires certain rigidity and stiffness, can be adapted to automatic packaging machinery packaging, heat sealing mechanical sealing, bag making, and easy to fill items, easy to uncover and other properties.

3. Delivery and storage performance. The package must have a certain compressive strength, and it is not easy to break when it is subjected to general pressure in the circulation field. The shape of the packaging should be convenient for stacking and occupy less space.

4. Promotional performance. The color of the packaging model should be novel, and the color of the decoration and printing should be bright and generous. In addition, it also requires no static electricity to prevent dust pollution.