Claims
- 1. A method for making fibers comprisinga) extruding filaments of fiber-forming material; b) directing the filaments through a processing chamber defined by two parallel walls, at least one of the walls being instantaneously movable toward and away from the other wall and being subject to movement means for providing instantaneous movement during passage of the filaments, processing of filaments through the processing chamber continuing essentially uninterrupted during the instantaneous movement of the wall(s) such that a substantially uniform web can be collected during the movement; and c) collecting the processed filaments.
- 2. A method of claim 1 further characterized in that the movement means comprises biasing means for resiliently biasing the at least one movable wall toward the other wall, the biasing means providing a biasing force that establishes a dynamic equilibrium between the pressure within the processing chamber and the biasing force such that the wall moves away from the other wall in response to increases in pressure within the chamber but is quickly returned to the equilibrium position by the biasing force upon resumption of the original pressure within the chamber.
- 3. A method of claim 1 further characterized in that the movement means comprises oscillating means for oscillating the at least one movable wall at a rapid rate so as to release extrudate that may accumulate on the walls of the chamber.
- 4. A method of claim 1 in which both parallel walls are instantaneously movable toward and away from one another and subject to movement means for providing instantaneous movement.
- 5. A method of claim 1 in which a fluid stream is established to direct the filaments through the processing chamber, and at least part of the fluid stream flows through one or more narrow slots disposed within the processing chamber and has a vector component along the longitudinal axis through the processing chamber.
- 6. A method of claim 1 in which the parallel walls have a length transverse to the direction of filament movement through the chamber substantially greater than the spacing between the walls.
- 7. A method of claim 6 in which the processing chamber is free of side walls at the ends of the transverse length of the parallel walls.
- 8. A method of claim 1 in which at least a majority of the filaments solidify before entering the processing chamber, whereupon the solidified filaments are subjected to a lengthwise orienting stress within the chamber.
- 9. A method of claim 1 in which at least a majority of the filaments solidify after they enter the processing chamber but before they exit the chamber.
- 10. A method of claim 1 in which at least a majority of the fibers solidify after they exit the processing chamber.
- 11. A method of claim 1 in which at least a majority of the fibers are sufficiently liquid when collected that fibers become adhered at points of fiber intersection.
- 12. A method of claim 1 in which fibers are collected at an apparent filament speed of at least 8000 meters per minute.
- 13. A method of claim 1 in which the fiber-forming material is extruded through a plurality of die orifices arranged side-by-side in at least one row, and the individual filaments are attenuated into microfibers having an average fiber diameter of about 10 micrometers or less.
- 14. A method of claim 1 in which fibers are collected at an apparent filament speed of at least 10,000 meters per minute.
- 15. A method of claim 1 performed at a productivity index as defined herein of at least 9,000.
- 16. A method of claim 1 in which the fiber-forming material comprises polypropylene, and the method is performed at a productivity index of at least 6500.
- 17. A method of claim 1 in which the fiber-forming material comprises polyethylene terephthalate, and the method is performed at a productivity index of at least 8400.
- 18. A method for making fibers comprisinga) extruding filaments of fiber-forming liquid through orifices in a die, b) directing the filaments through an attenuation chamber defined by two parallel walls, at least one of the walls being instantaneously movable toward and away from the other wall and being resiliently biased toward the other wall; c) establishing a fluid stream that carries the filaments between the walls and attenuates them into fibers; d) selecting a biasing force on the at least one movable wall that establishes a dynamic equilibrium between the pressure within the attenuation chamber and the biasing force such that the wall moves away from the other wall in response to increases in pressure within the chamber but is quickly returned to the equilibrium position by the biasing force upon resumption of the original pressure within the chamber; and e) collecting the formed fibers.
- 19. A method of claim 18 in which both parallel walls are instantaneously movable toward and away from one another and connected to biasing means for providing such instantaneous movement.
- 20. A method for making fibers comprisinga) extruding filaments of fiber-forming material; b) directing the filaments through a processing chamber defined by two parallel walls, at least one of the walls being instantaneously movable toward and away from the other wall and being subject to movement means for providing instantaneous movement during passage of the filaments; and c) collecting the processed filaments; the movement means comprising biasing means for resiliently biasing the at least one movable wall toward the other wall, the biasing means providing a biasing force that establishes a dynamic equilibrium between the pressure within the processing chamber and the biasing force such that the wall moves away from the other wall in response to to increases in pressure within the chamber but is quickly returned to the equilibrium position by the biasing force upon resumption of the original pressure within the chamber.
REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No. 09/716,786, filed Nov. 20, 2000 now abandoned.
US Referenced Citations (50)
Foreign Referenced Citations (5)
Number |
Date |
Country |
40 14 414 |
Jul 1991 |
DE |
42 10 464 |
Oct 1993 |
DE |
WO 0028123 |
May 2000 |
WO |
WO 0065134 |
Nov 2000 |
WO |
WO 02055782 |
Jul 2002 |
WO |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09/716786 |
Nov 2000 |
US |
Child |
09/835904 |
|
US |