Paper used to pack all kinds of goods and materials. Generally has a high physical strength and a certain degree of water resistance. According to the characteristics of products, packaging paper has corresponding special properties (see table). Packaging paper, the amount of the largest is the packaging of bulk powder granular industrial and agricultural raw materials, such as cement, fertilizer and other paper bag paper, generally made of more than 3 to 4 layers of paper, it is also known as multi-layer paper bag paper, to distinguish from the packaging of light and fine goods of other bag paper. This kind of wrapping paper mainly requires high strength, heavy load resistance, impact resistance, and appropriate air permeability. Food packaging paper of the largest variety of specifications. And divided into internal packaging and external packaging with two categories. Direct contact with food called packaging paper, the main requirements of cleaning, do not carry bacteria, with moisture-proof, oil-proof, stickproof, mildew and other characteristics. Outside wrapping paper is mainly for beautification and protection of goods, in addition to the requirements of a certain physical strength, but also need to be clean and beautiful, suitable for the printing of multi-color commodity patterns and text. For milk, vegetable juice and other liquid beverage packaging paper, but also must have excellent permeability. In order to meet the needs of long-term preservation and freshness preservation, special soft packaging paper for beverage (see food packaging container), which is composed of paper and metal film, paper and plastic and metal film, has been developed in recent years. Antirust paper was developed to meet the needs of metal instruments and tools. Most of the cardboard is also used for commodity packaging, mainly used in the manufacture of cartons, cartons and packaging liner.