DOP refers to dioctyl phthalate, its physico-chemical property is the colorless oily liquid with characteristic odor. The specific gravity: 0.986 (20 ℃), boiling point: 386.9 ℃ (760mmHg), flash point: 219 ℃, ignition point: 241 ℃ and so on. Both contain organic solvents and hydrocarbons, which are harmful gases. If they are discharged directly to the outside without any control measures, it will pollute the environment and endanger human health. Therefore, they should be controlled.