The sandwich packaging box basic materials used in paper containers are: (1) kraft paper is made from kraft pulp made from softwood thick fibers. The strength of the paper is higher than that of ordinary paper, and can be used for large paper bags to pack sugar, flour and rice. Kraft paper treated with synthetic resins has moisture resistance and oil resistance. Sulfuric acid paper is used to treat paper with sulfuric acid, so that the surface of its fiber forming colloidal starch cellulose, with high strength, moisture resistance, oil and heat resistance, sterilization temperature characteristics. Can be used for oily food, frozen food packaging, and sometimes in the inner packing paper liner. The paper, with low melting point paraffin treated, with moisture, oil resistance and sealing characteristics of the. It is used as the cheapest packing material for all kinds of high and low grade foods.