FILTERING MATERIAL FOR FILTER AND PRODUCTION PROCESS THEREFOR

摘要

In this production process, papermaking is conducted using a first papermaking raw material for an upper layer and a second papermaking raw material for a lower layer so as to create a continuous density gradient from the upper layer to the lower layer. Each papermaking raw material comprises both a natural fiber such as pulp and a chemical fiber such as PET. The chemical fiber content of the first papermaking raw material is higher than that of the second papermaking raw material, while the fiber diameter of the chemical fiber contained in the first papermaking raw material is larger than that of the chemical fiber contained in the second papermaking raw material. Thus, a filtering material which can retain particles having a wide diameter range and which suffers from little clogging and thus exhibits a prolonged life can be obtained.