Process for preparing fiber, rovings and mats from lyotropic liquid crystalline polymers

DETAILED DESCRIPTION OF THE INVENTION Optically anisotropic solutions are useful in the present invention and are well known in the art.
Such solutions include poly(p-phenylene terephthalamide) (PPD-T) in concentrated sulfuric acid as disclosed in U.
S.
Pat.
Nos.
3,767,756 and 3,869,429 and cellulose triacetate in trifluoroacetic acid as disclosed in U.
S.
Pat.
No.
4,464,326.
If desired, polymers that do not form anisotropic solutions on their own, may be incorporated in the aforementioned anisotropic solutions before extrusion to form polymer blends or molecular composites of the polymers.
Such added polymers include nylon 6/6, the amorphous polyamides prepared from a mixture of terephthalic acid, isophthalic acid, bis(p-aminocyclohexyl)methane and hexamethylene diamine and copolymers prepared from 3,4'-diaminodiphenyl ether, and isophthaloyl bis(caprol The solutions can be prepared by techniques understood by those skilled in the art.
The solution is extruded through a spinneret orifice into a chamber in the vicinity of an aperture, generally convergent-walled through which it will exit the chamber.
A pressurized gas which is inert to the anisotropic solution, is introduced into the chamber also in the vicinity of the aperture and in surrounding contact with the solution stream.
The gas, preferably air, is conveniently at a pressure between 3.
0 kg/sq.
cm.
and 5.
0 kg/sq.
cm.
and is at a temperature of from 20.
degree.
C.
to 120.
degree.
C.
- as it is fed into the chamber.
The velocity of the gas is such as to attenuate and fragment the stream as it exits the chamber through the aperture.
The gas and stream upon leaving the chamber, enter a zone of lower pressure, preferably air at atmospheric pressure.
It is in this zone that the fragmented stream is contacted either before or after collection, with a jet of coagulating fluid.
In order to prepare a mat, the fragmented stream is contacted with a jet of coagulating fluid, for example, water, at some distance such as 15 to 30 centimeters from the aperture