Method for spinning a polybenzazole fiber
AssigneeThe Dow Chemical Company
InventorsChieh-Chun Chau, Timothy L. Faley, Michael E. Mills, Masaru Nakagawa, Timothy J. Rehg, Myrna Serrano, Ravi Shanker, George J. Quarderer, Jr., Yoshihiko Teramoto
Life of this patent
Estimating the term…
Abstract
Polybenzazole polymer dopes are spun into fibers at high speed by passing through a spinneret with proper selection of hole geometry, followed by spin-drawing to a spin-draw ratio of at least 20, washing, taking up and drying. The take up speed is at least about 150 meters per minute, and the fibers are spun in at least 10 km lengths without a break.
Claims19
A process to spin a fiber from a liquid-crystalline dope that contains a solvent polyphosphoric acid and a lyotropic polybenzazole polymer which is polybenzoxazole, polybenzothiazole or a copolymer thereof, said process comprising the steps of:
- (1) spinning the dope through a spinneret that contains:
- (1) two faces and (2) a plurality of holes through which the dope may pass from one face to the other, wherein:
- (a) each hole contains an inlet by which dope enters the hole, a capillary section, and an exit by which dope leaves the hole, and
- (b) the entry to the capillary section and the diameter of the capillary section are selected to spin on average at least about 10 km of finished filament, with no more than about one break per 10 km of filament spun;
- whereby a plurality of dope filaments is formed;
- and
- (2) drawing the dope filaments across a draw zone with a spin-draw ratio of at least about 20;
- and
- (3) in any order (a) washing a major part of the polyphosphoric acid from the filaments, (b) drying the washed filaments and (c) taking up the filaments at a speed of at least 150 meters per minute whereby filaments that have an average diameter of no more than about 18 .mu.m per filament are formed with on average no more than about one break per 10 km of filament.
Dependencies are inferred from the claim text.