Process for the manufacture of polyetherketoneketone fiber
A process for manufacturing a fiber including polyetherketoneketone including the steps of: mixing polyetherketoneketone and sulfuric acid having a concentration of at least 90 wt % to obtain a spin dope and passing the spin dope through a spinneret into a coagulation bath, wherein the polyetherketoneketone is dissolved in the sulfuric acid to a concentration of 12 to 22 wt %. Also disclosed are fibers obtainable by the process and polyetherketoneketone fibers having a sulfur content of 0.001 to 5 wt %, based on the weight of the fiber, in particular such fibers having low or high crystallinity, as well as, hybrid yarns and composite materials.
1. A process for manufacturing a polyetherketoneketone fiber comprising the steps of:
mixing polyetherketoneketone and sulfuric acid having a concentration of at least 90 wt % to obtain a spin dope and passing the spin dope through a spinneret into a coagulation bath, wherein the polyetherketoneketone is dissolved in the sulfuric acid to a concentration of 12 to 22 wt %,
wherein the spin dope comprises a polymer fraction and at least 60 wt % of the polymer fraction is polyetherketoneketone.
2. The process according to claim 1 , wherein the polyetherketoneketone comprises repeating units represented by Formula I and Formula II:
-A-C(═O)—B—C(═O)— I
-A-C(═O)-D-C(═O)— II,
where A is a -Ph-O-Ph- group, where Ph is a phenylene radical, B is 1,4-phenylene and D is 1,3-phenylene and wherein the ratio of repeating units represented by Formula I:Formula II is 100:0 to 0:100.
3. The process according to claim 1 , wherein the polyetherketoneketone has a melting temperature T m which is at least 295° C.
4. The process according to claim 1 further comprising heating the fiber in at least one heating step to a temperature in the range of 150 to 290° C.
5. The process according to claim 4 , wherein during heating step, a tension is applied which results in a drawing ratio of 1.5 to 10.
6. The process according to claim 4 , wherein the fiber is heated in a second heating step to a temperature in the range of 150 to 290° C.
7. The process according to claim 6 , wherein during the second heating step a tension is applied which results in a drawing ratio of the fiber of at most 1.5.
8. The process according to claim 1 , wherein the fiber after coagulation is only treated with solutions having a pH of at most 11.
9. The process according to claim 1 , wherein the spin dope comprises a polymer fraction and at least 70 wt % of the polymer fraction is polyetherketoneketone.
10. The process according to claim 1 , wherein the spin dope comprises a polymer fraction and at least 90 wt % of the polymer fraction is polyetherketoneketone.