Synthetic paper is categorized by its production material, including PP, HDPE, PS, PVC, PET, ABS, and more. It is also divided by the type of filler, such as calcium carbonate (CaCO3), clay (mainly SiO2, Al2O3), silica (SiO2), talc, titanium dioxide (TiO2), and composite (two or more fillers). Production methods vary, including calendering (e.g., soft PVC), casting (e.g., CPP), blowing (e.g., HDPE), and biaxial stretching (e.g., BOPP, BOPET). By structure, it is classified into single-layer, triple-layer, and five-layer synthetic paper, among others.