Printing ink consists of pigment, adhesive, solvent and auxiliary agent. Among them, organic solvents and heavy metal elements are seriously harmful to human body. There are two kinds of pigments in ink-inorganic and organic, which are insoluble in water and other media and have bright colors and stability. Some inorganic pigments contain heavy metal elements such as lead, chromium, copper and mercury, which are toxic and cannot be used for printing food packaging and children's toys. Some organic pigments contain biphenyl glue, which is carcinogenic and should be strictly prohibited. Organic solvents can dissolve many natural resins and synthetic resins, which are important components of various inks, but some of them will damage human body and subcutaneous fat. Long-term contact will make the skin chapped and rough. If it penetrates into the skin or blood vessels, it will harm people's blood cells and hematopoiesis with blood. Inhalation into trachea, bronchus, lung or spread to other organs through blood vessels and lymphatic vessels may even cause chronic poisoning. Some inks are toxic to heavy metal ions, and pigments and dyes contain carcinogenic components, which are very harmful to human health. A large number of inks, organic solvents and adhesives are used in the printing of composite packaging materials. Although these auxiliary materials are not in direct contact with food, some toxic substances will migrate into food during the packaging and storage of food, which will endanger people's health. Organic solvents such as ethanol, isopropanol, butanol, propanol, butanone, ethyl acetate, butyl acetate, toluene and xylene are often used in printing inks. Although most of these solvents can be removed by drying, the residual solvents will migrate to food and cause harm to human body. The solvents used in gravure printing ink generally include butanone, xylene, toluene, butanol, etc. Especially butanone, has a strong residual odor. Because the pigment particles in ink are very small and have strong adsorption, although it has been heated and dried during printing, it is often incomplete because of its short time and high speed, especially for printed matter with large inking area and thick ink layer, there are more residual solvents. These residual solvents are brought into the compounding process, which is more difficult to escape after compounding, and will slowly migrate and permeate, so the solvent residue must be controlled to a minimum.