Fibers and fiber spinnerets

Abstract

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.

What is claimed is: 
     
         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.