Polyester filter bags are used to treat air pollution and material recovery, and are suitable for operation at temperatures between 125 C and 140 C. The polyester needle-punched filter felt is a layered composite product of a textile woven fabric and a nonwoven needle-punched nonwoven fabric. In the middle layer of the filter material, there is a woven base fabric layer which acts as a reinforcing steel frame to increase the strength. On the surface of the base fabric with a small tightness, the fiber-woven woven layer is laminated. The product has a three-dimensional structure, and its total opening ratio can reach more than 80%. The surface of the needle-punched cloth is arranged in a single fiber layer, and the number of cloth faces is large, the aperture is small, and the distribution is uniform, and the dust collection effect is good. Therefore, the needle felt has the advantages of high dust-pumping efficiency, good air permeability, low resistance and high air volume capacity. Polyester (polyester) fiber filter material is used for temperatures from 125 C to 140 C. The polyester has excellent electrical insulation, good wear resistance, high strength and good elastic recovery performance, and the strength loss at 170 C can be recovered in a short time, and the thermal stability is good. Polyester has poor hygroscopic properties and is easily hydrolyzed. It is more easily eroded under the conditions of containing sulfuric acid, nitric acid and carbonic acid. It is stable to low concentration of inorganic acid under low temperature conditions, but it is soluble in concentrated sulfuric acid and heated formic acid. It is stable to general organic solvents, has good resistance to weak bases, and is generally resistant to strong alkalis.