FIBERS AND FIBER SPINNERETS
A method including the steps of extruding a melt including an amorphous polymer composition through a spinneret under a pressure of from 400 to 1500 psi to produce a spun fiber; collecting the spun fiber on a feeding roll without drawing the spun fiber; producing a solidified fiber from the spun fiber. The solidified fiber can have a dpf within a range of from greater than 0 to 2.5 dpf, and a shrinkage less than or equal to 2%. The method can also include collecting the solidified fiber onto a spool without subjecting the solidified fiber to a drawing step. A spinneret for producing fibers of at most 2.5 dpf from a composition comprising an amorphous polyetherimide polymer, the spinneret comprising a die having a plurality of round melt channels but no distribution plates. Fibers produced by the method and from the spinneret are also disclosed.
1 . A method comprising:
extruding a melt through a spinneret under a pressure of from 400 to 1500 psi to produce a spun fiber,
wherein the melt comprises an amorphous polymer composition;
collecting the spun fiber on a feeding roll without drawing the spun fiber, producing a solidified fiber from the spun fiber,
wherein the solidified fiber has a dpf within a range of from greater than 0 to 2.5 dpf,
wherein the solidified fiber has a shrinkage less than or equal to 2%; and
winding the solidified fiber onto a spool without subjecting the solidified fiber to a drawing step.
2 . The method according to claim 1 , wherein the amorphous polymer composition has a melt flow rate of from 4 to 18 g/10-min.
3 . The method according to claim 1 , wherein the pressure is from 400 to 1000 psi.
4 . The method according to claim 1 , further comprising collecting the fiber onto the spool without an annealing step.
5 . The method according to claim 1 , wherein the solidified fiber is produced without a forced-air cooling step.
6 . The method according to claim 1 , wherein the process further comprises heating the spun fiber after it exits the spinneret.
7 . The method according to claim 1 , wherein the melt comprises one or more crystalline materials.
8 . The method according to claim 1 , wherein the amorphous polymer composition comprises a polyetherimide.
9 . An undrawn amorphous polymer fiber having a denier less than 2.5 and a shrinkage of from greater than 0 to less than or equal to 2%.
10 . The undrawn amorphous polyetherimide fiber of claim 9 , wherein the fiber has a polydispersity (Mw/Mn) greater than or equal to 2.5.
11 . The undrawn amorphous polyetherimide fiber of claim 9 , wherein the fiber has a denier less than 2.2.
12 . The undrawn amorphous polyetherimide fiber of claim 9 , wherein the fiber has a denier less than 2.0.
13 . The undrawn amorphous polyetherimide fiber of claim 9 , wherein the fiber has a strength of at least 2.6 cN/dtex.
14 . The undrawn amorphous polyetherimide fiber of claim 9 , wherein the fiber is unnannealed.
15 . An article comprising the undrawn amorphous polyetherimide fiber of claim 9 .
16 . A fiber comprising an unnannealed amorphous polyetherimide fiber of claim 9 .
17 . A manufacture comprising the fiber of claim 9 .
18 . A spinneret for producing an amorphous undrawn polyetherimide fiber of at most 2.5 dpf from a composition comprising an amorphous polyetherimide polymer, the spinneret comprising
no distribution plates;
a die having a plurality of round melt channels, wherein each round melt channel has a length and a diameter, and wherein the ratio of length:diameter of each round melt channel is from 2:1 to 6:1.
19 . The spinneret of claim 18 , wherein the spinneret operates at a pressure that is at least 40% less than an operating pressure of an identical spinneret comprising distribution plates.
20 . The spinneret of claim 18 , wherein the spinneret further comprises at least one screen pack filter coupled to the die to distribute the composition to the die.
21 . The spinneret of claim 20 , wherein the screen pack filter has a US mesh size of from 200 to 400 mesh.