Talc is an aqueous, layered silicate mineral. Chemical formula: Mg3(Si4O10)(OH)2. Its chemical composition: MgO is 31.8%, SiO2 is 63.37%, H2O is 4.7%, and often contains a small amount of Fe, A1 and other elements. The density of talc is 2.7~2.8g/cm, the hardness is the smallest among the mineral deposits, the Mohs hardness is 1, and it has a soft and smooth feeling. Its colors are white, gray-green, milky white, light red, light blue, light gray, etc., with pearl or fat luster. The water of association can be lost at 380~500℃, and the water of crystallization is lost when the temperature is above 800℃. Talc is slightly alkaline in water with a pH of 9.0~9.5. Talc has a layered structure, and two adjacent layers are bound by weak van der Waals forces. Under the effect of external force, it is easy to slip between two adjacent layers or to separate from each other. Therefore, the basic shape of the talc particle structure is flaky or scaly.

The flake-like structure of talc makes some functions of talc-filled plastics greatly improved, and some people regard talc as a reinforcing filler. The main talc powder can improve the stiffness and creep resistance of the filling material at high temperature. When the talc particles are placed along the moving direction of the material during processing, according to the principle of less resistance, they are basically placed in the form of flakes, which are connected by small pieces into large pieces. Therefore, the stiffness of the material can be significantly improved in a specific direction. Secondly, talcum powder can significantly improve the heat resistance of filling materials. The heat distortion temperature used to measure the heat resistance of the material refers to the temperature at which the sample is bent to a certain extent under the load. Among the silicon-containing fillers, the price of talc is relatively low, which can reduce the cost.