Apparatus for making spunbond

An apparatus for making spunbond from continuous thermoplastic filaments, the apparatus comprising:

• a spinneret for spinning the continuous filaments and advancing them in a downward filament-travel direction;
• a cooler for cooling the filaments;
• a stretcher for stretching the filaments;
• a depositing device including a foraminous belt extending and traveling in a machine direction transverse to the filament-travel direction and defining a deposition region for deposition of the filaments as a nonwoven web and conveyance away from the stretcher in the machine direction;
• a diffusor between the stretcher and the foraminous belt, receiving the filaments and primary air from the stretcher in the filament-travel direction, and having relative to the filament-travel direction
• a downstream section that diverges in the filament-travel direction, and
• an upstream section that converges in the filament-travel direction,
• the diffusor forming relative to the machine direction upstream and downstream secondary air-inlet gaps at opposite ends of the diffusor through which secondary air is aspirated into the diffusor, the upstream and downstream secondary air-inlet gaps being oriented such that the secondary air flows in at an inflow angle αof less than 65° with respect to the filament-travel direction or with respect to a longitudinal central plane of the depositing device or of the diffusor, the downstream section having walls diverging in the filament-travel direction toward the depositing device and forming a diffusor outlet having an outlet width in the machine direction;
• and
• a suction device having two partitions spaced apart in the machine direction by an extraction width for extracting air or process air through the foraminous belt at an extraction region underneath the diffusor outlet between the partitions, the extraction width in the machine direction being at least 1.7 times the outlet width in the machine direction of the diffusor outlet, the extraction by the suction device taking place such that at least in the region of the diffusor outlet tertiary air flows along outer surfaces of the diffusor walls toward the depositing device or the foraminous belt.