Process for the production of polyarenazole yarn
View Patent ↗The present invention concerns a process for making a polyareneazole multifilament yarn comprising: a) extruding a solution comprising polyareneazole polymer and polyphosphoric acid through a plurality of orifices to produce filaments; b) forming a multifilament yarn from said filaments; c) hydrolyzing at least some of the polyphosphoric acid in the yarn by heating the yarn to a temperature above about 120° C. for up to about two minutes; d) washing at least some of the hydrolyzed polyphosphoric acid from the yarn; e) drying the washed yarn; f) optionally, heating the yarn above about 300° C., and g) collecting the yarn at a speed of at least about 50 meters per minute.
1. A continuous process for making a polyareneazole multifilament yarn comprising:
a) extruding a solution comprising polyareneazole polymer and polyphosphoric acid through a plurality of orifices to produce dope filaments;
b) passing the dope filaments of step (a) through an air gap and then through a coagulation bath to convert the dope filaments to substantially solid polymer filaments and form a multifilament yarn from said substantially solid polymer filaments;
c) hydrolyzing in a separate step at least some of the polyphosphoric acid in the substantially solid polymer filaments in the yarn by heating the yarn of step (b) to a temperature above about 150° C. for up to about two minutes;
d) washing at least some of the hydrolyzed polyphosphoric acid from the yarn of step (c);
e) drying the washed yarn of step (d);
f) optionally, heating the yarn above about 300° C., and
g) collecting the yarn at a speed of at least about 50 meters per minute.
2. The process of claim 1 additionally comprising conditioning the yarn prior to said hydrolyzing.
3. The process of claim 2 wherein conditioning comprises removing surface liquid from the yarn.
4. The process of claim 3 wherein the yarn are rinsed with an aqueous solution prior to removal of surface liquid.
5. The process of claim 1 wherein the solution is a liquid crystalline solution.
6. The process of claim 1 wherein the polyareneazole polymer is formed from azole-forming monomers, said monomers being 2,5-dimercapto-p-phenylene diamine, terephthalic acid, bis-(4-benzoic acid), oxy-bis-(4-benzoic acid), 2,5-dihydroxyterephthalic acid, isophthalic acid, 2,5-pyridodicarboxylic acid, 2,6-napthalenedicarboxylic acid, 2,6-quinolinedicarboxylic acid, 2,6-bis(4-carboxyphenyl) pyridobisimidazole, 2,3,5,6-tetraaminopyridine, 4,6-diaminoresorcinol, 2,5-diaminohydroquinone, 2,5-diamino-4,6-dithiobenzene, or any combination thereof
7. The process of claim 5 wherein said azole-forming monomers are 2,3,5,6-tetraaminopyridine and 2,5-dihydroxyterephthalic acid.
8. The process of claim 1 wherein at least some of the polyphosphoric acid in the yarn is hydrolyzed by heating the yarn to a temperature above about 180° C.
9. The process of claim 8 wherein at least some of the polyphosphoric acid in the yarn is hydrolyzed by heating the yarn to a temperature above about 200° C.
10. The process of claim 1 wherein said washing comprises contacting the yarn with aqueous base.
11. The process of claim 1 wherein said washing comprises contacting the yarn with aqueous base followed by aqueous acid.
12. The process of claim 1 wherein said washing comprises contacting the yarn with water.
13. The process of claim 1 wherein the yarn is dried to less than about 20 percent water content by weight.
14. The process of claim 1 wherein the yarn is heated in step f) to a temperature of about 400° C. or greater.
15. The process of claim 1 wherein the yarn is collected at a speed of at least about 100 meters per minute.
16. The process of claim 1 wherein the yarn is collected at a speed of at least about 250 meters per minute.
17. The process of claim 1 wherein the yarn is collected at a speed of at least about 500 meters per minute.
18. The process of claim 1 wherein the yarn is collected at a speed of at least about 800 meters per minute.