The main application range of vacuum packaging bags is in the field of food, and it is used in the range of food that needs to be sto in a vacuum environment. It is used to extract air from plastic bags, and then add nitrogen or other mixed gases that are not harmful to food. The main functions of vacuum packaging bags: vacuum packaging bags, tea packaging bags Inhibition of microbial growth environment. 2. The vacuum packaging bag can prevent the moisture of the food from evaporating, uce the loss of water and maintain the quality of the product. 3. The aesthetics of the vacuum packaging bag itself makes it easy for people to have an intuitive feeling about the product and increase the desire to buy. Let’s talk about the specific selection of vacuum packaging bags. The vacuum packaging bags are made of polyvinylidene chloride, polyester and polyamide materials that are anti-oxidative, that is, prevent oxygen permeability and good shrinkage; some of them will be composited with nylon, polyester film and polyethylene multi-layer materials. The polyvinylidene chloride material mentioned above is the type of film with the best effect of blocking oxygen and water vapor, but it is indeed not resistant to heat sealing. Polyester has great tensile strength. Nylon has good oxygen barrier properties and good heat resistance, but the water vapor transmission rate is too large and the manufacturing cost is high. Therefore, in general, most manufacturers will choose composite bags materials to choose the advantages and disadvantages of various films.