Process and apparatus for producing a spun-fiber web from synthetic polymer
Assigneesilver plastics GmbH & Co. KG
InventorHans Reifenhauser
Life of this patent
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Abstract
A process and an apparatus for producing a spun-fiber web from filaments of a synthetic polymer which includes a device for taking off the filaments and a web-depositing device with suction unit wherein the filaments are taken off mechanically by means of a take-off roll with a unit for the defined raising of the frictional force between the roll surface and the filaments, the filaments being exposed, in particular, to a vacuum and/or to pressurized air.
Claims19
A process for the production of a spun-fiber web from filaments of a synthetic polymer wherein the filaments exiting through spinnerets from a molten mass of synthetic polymer are guided through a cooling well traversed by cooling air and, after cooling and strengthening, are conducted over a portion of a surface of at least one take-off roll;
- and thereafter the filaments are swirled and deposited on a depositing conveyor belt to form said web, characterized in that a conveying velocity of a take-off roll at which the filaments arrive is controlled to be substantially higher than an exit speed of the filaments from the spinnerets;
- the filaments resting on the surface of the take-off roll, are exposed in a pressing zone to compressed air acting from the outside on the surface of the take-off roll, and are pressed against the surface of the take-off roll whereby adhesive friction of the filaments on the take-off roll is increased;
- and the filaments are accelerated by rotation of the take-off roll so that the exit cross section of the filaments exiting the spinnerets is reduced at a state of the synthetic polymer of the filaments which, in the case of partially crystalline polymers, is in a range above the crystallite melting zone of the synthetic polymer and which, in case of amorphous synthetic polymers, is in a range above the softening temperature zone of the synthetic polymer;
- the filaments initially pressed against the surface of the take-off roll in the pressing zone are lifted off from the surface of the take-off roll at the end of the pressing zone by streams of compressed air acting from the interior of the take-off roll through perforations in the surface of the take-off roll on the filaments;
- and the adhesive friction of the filaments on the surface of the take-off roll is increased in the pressing zone by exposing the filaments to a vacuum from an interior of the take-off roll;
- the vacuum being generated in a suction chamber in the interior of the take-off roll and acting on the filaments via the perforations in the surface of the take-off roll and the compressed air acting from outside on the surface of the take-off roll being exhausted partially via the suction chamber in the interior of the take-off roll;
- and the compressed air acting from the interior of the take-off roll through the perforations in the surface of the take-off roll to lift off the filaments at the end of the pressing zone being fed from a discharge side of a fan creating the vacuum in the suction chamber.
An apparatus for the production of a spun-fiber web from filaments of a synthetic polymer extruded through spinnerets of a die head which comprises an extruder for extruding the synthetic polymer through the die head;
- a cooling well adjoining the spinnerets, which is exposed to air, for cooling the filaments;
- at least one take-off roll arranged downstream of the cooling well for withdrawing the fibers from the spinnerets, the filaments being guided along a looping path distance on a surface of a perforated wall of the at least one take-off roll;
- and means for forming a random array of the filaments into said spun-fiber web, characterized in that a take-off roll for initially receiving the filaments has drive means controllable in dependence on an exit speed of the filaments from the spinnerets for effecting rotation of the first take-off roll whereby peripheral speed of the first take-off roll corresponds to the conveying velocity of the filaments, the drive means being controlled in such a way that the conveying velocity of the filaments is substantially higher than the exit speed of the filaments from the spinnerets;
- means for increasing the frictional force between the surface of the first take-off roll and the filaments guided thereon in a zone of the looping path distance of the filaments, said means for increasing the frictional force including a unit positioned outside the take-off roll for directing compressed air onto the filaments to press the filaments against said surface;
- an exhaust chamber arranged in the interior of the first take-off roll at the end of the looping path distance, said exhaust chamber having exhaust openings for directing compressed air towards the perforated wall of the take-off roll to pass the compressed air through perforations and to lift the filaments off the surface of the take-off roll;
- the take-off roll comprising a suction drum which has in its interior a suction chamber associated with the zone of the looping path distance of the filaments for applying suction to the filaments through the perforated wall to also increase the functional force of the filament against the drum surface and the exhaust chamber being connected via conduits to an exhaust side of a fan for applying a vacuum to said suction chamber.
Dependencies are inferred from the claim text.