Multilayer filter medium for use in filter, and filter

Abstract

A multilayer filter medium, which is used as a constituent member of a filter and has a multilayer structure, includes a wet type nonwoven fabric layer A containing 0.5 to 20% by weight, based on layer weight, of short-cut nanofibers which are composed of a fiber-forming thermoplastic polymer, have a single fiber diameter (D) of 100 to 1,000 nm and are cut so that the ratio (L/D) of the length (L) to the single fiber diameter (D) is within the range of 100 to 2,500 and core-sheath conjugate type binder fibers having a single fiber diameter of 5 μm or more, and a nonwoven fabric layer B having a lower density than that of the wet type nonwoven fabric layer A. A filter uses the multilayer filter medium and has the nonwoven fabric layer B arranged on a fluid inlet side.

Dependencies are inferred from the claim text.