The monofilaments are picked up directly underneath the spinneret by a gas stream (normally air), which draws them by applying shear stresses to the surface. In contrast to all meltblown processes both the melt and air flows are steadily accelerated. As soon as the internal pressure pF in the monofilament exceeds the external gas pressure pG the NANOVAL effect causes the filament to burst spontaneously. The permanent increase of the internal pressure pF is due to shear forces between the faster gas flow and the filament’s sheath, its skin, inducing an increasing pressure inside the still liquid filament. This pressure acts against the monofilament’s sheath and it can split into a multitude of up to several 100 finer filaments per spinhole.
Nonwovens can be produced from spliced continuous filaments. The spin-neret nozzles are arranged in rows or as single spin-cones in several parallel rows. The filaments can be deposited on a collector belt running below, at the same time removing the gas/air from underneath the belt by a suction fan.
The process is simple, robust in operation and energy saving. Filaments can reach diameters below 1 µm.
The process is patented.