Patent ID: 6358417
Filing Date: 2002-03-19
Classification: B01D,D04H

Abstract:
A composite filament mass for use in constructing a depth filter element, the composite filament mass comprising:a first cylindrical mass of essentially continuous, intertwined, and thermally bonded polymer filaments, the polymer filaments of the first cylindrical mass having diameters of less than about 1.5 microns; wherein the first cylindrical mass comprises a first filament zone and a second filament zone, the first filament zone defining a calendered layer having a density of filaments which is substantially greater than that of the second filament zone; the calendered layer defining a smooth inner cylindrical surface of the composite filament mass; and a second cylindrical mass of essentially continuous, intertwined, and thermally bonded polymer filaments surrounding the first cylindrical mass of polymer filaments, the polymer filaments of the second cylindrical mass having diameters greater than about 1.5 microns, wherein the diameter of the polymer filaments in each cylindrical mass is less than the diameter of the polymer filaments in each surrounding cylindrical mass.