Patent ID: 6916395

Claim:
A method of continuously producing a melt-blown polymer filament mass comprising: continuously producing a first set of melt-blown polymeric filaments, the first set being produced generally in-line along an axis generally parallel to a rotating collection device, wherein continuously producing the first set of melt-blown polymeric filaments comprises: extruding polymeric material through a first nozzle to create a first polymer stream, the first polymer stream being generally perpendicular to an axis of rotation of the collection device; and exposing the first polymer stream to a first attenuating gas stream; continuously collecting the first set of filaments directly on the rotating collection device to form a tubular filament mass having a plurality of layers; applying a second set of melt-blown polymeric filaments to the filament mass from a source positioned at an acute angle relative to an axis of rotation of the collection device, the second set being deposited on the filament mass such that polymeric filaments of the second set extend through and engage a plurality of layers of the polymeric filaments of the first set, wherein applying the second set of melt-blown filaments comprises: extruding polymeric material through a second nozzle to create a second polymer stream, the second nozzle being closer to the collection device than the first nozzle; and exposing the second polymer stream to a second attenuating gas stream; and urging the filament mass along the rotating collection device, the filament mass having indefinite length with a first major surface and a second major surface, the first major surface being adjacent the collection device.