The oily liquid used when sticking the toughened film is silicone oil. Silicone oil is used on the surface of irregular objects to protect the surface. The formed film can prevent dirt, rust, acid and alkali erosion and wear, and protect the smoothness and durability of the surface of the object. Silicone oil has good permeability and lubricity, which makes the toughened film better attached to the surface of the object and provides an extra protective layer.