| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonwoven fabric which can keep pressure loss low while demonstrating high collection efficiency, and which can be suitably used for an air filter; and to provide a filter medium obtained by using the same.SOLUTION: A mixed-fiber nonwoven fabric comprises a monolayer mixed-fiber nonwoven fabric containing fibers having different single fiber diameters. When a group comprising fibers having a single fiber diameter of 0.3-10 μm is defined as a fiber group A, and a group comprising fibers having a single fiber diameter of 60-120 μm is defined as a fiber group B, the mixed-fiber nonwoven fabric is evenly divided into four regions of (1)-(4) in this order from a front surface side. The fiber group A having a smaller fiber diameter is densely distributed in both regions of the front surface side (1) and the back surface side (4), so that distribution densities therein are higher than densities in (2) and (3) of central regions, but at the same time, the fiber group A is also present in each of the central regions (2) and (3). The mixed-fiber nonwoven fabric has a basis weight of 80-200 g/mand contains the fiber group A in a proportion of 15-40 vol.% and the fiber group B in a proportion of 60-85 vol.% in a unit volume.SELECTED DRAWING: None |
