Filter bags made of PAN needle felt with PI fibers (polyimide) admixture form a material with very precise filtration properties.
There are many methods of improving the filtration efficiency of acrylic materials. Often, microfibers are used which, by virtue of their structure and a special needling method, result in a filter medium with smaller pores. However, this happens at the expense of air permeability, which is also restricted.
The PI fibers admixture, with its typical, irregular design, provides good air permeability while maintaining high filtration efficiency.