Many of the answers are: in order to improve the weakness of the PPS filter material itself, poor resistance to oxidation.
It is impossible to completely “wrap” the PTFE emulsion by impregnating the filter fiber. The oxidized surface of the PPS fiber still exists. So far, there is no application example that proves that the PTFE-impregnated PPS filter bag will last longer than the immersed PPS filter bag under the same flue gas oxidation conditions.
The PTFE immersion treatment may improve the performance of the filter material: first, the surface of the smooth PPS fiber may be roughened (because the impregnation may not be very uniform), and the filtration efficiency of the PPS filter material may be improved. However, the non-stick characteristics of PTFE itself may also make it easier for the dust in the flue gas to “slide into” between the filter materials with the pressure of the flue gas, resulting in an irreversible increase in the running resistance of the filter material. Second, the characteristics of the PTFE are utilized. To improve the deashing performance of PPS filter material during cleaning.
In fact, it is more helpful to improve the deashing performance of the filter material by treating the surface of the PPS filter material with water and oil. Of course, the waterproof and oil-repellent treatment technology on the surface of the filter material is more difficult to process than the simple immersion in the PTFE emulsion.
In particular, it is necessary to object to the fact that some manufacturers take advantage of PTFE impregnation treatment to increase the actual weight of the filter material, which will harm the interests of users. Internationally, the weight of the filter material refers to the weight of the weight without any post-treatment.