# US 9,518,341 B2 · Method of producing an amorphous polyetherimide fiber and heat-resistant fabric > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,341 B2 - Document ID: US9518341B2 - Status: Granted - Kind: B2 - Application number: 14/539,657 - Filed: 2014-11-12 - Published: 2015-03-12 - Granted: 2016-12-13 - Earliest claimed: 2009-03-26 - Assignees: Kuraray Co., Ltd. - Applicants: Kuraray Co., Ltd. - Inventors: Ryokei Endo; Yosuke Washitake; Yukie Sugihara; Akihiro Uehata - Web page: https://patentgrep.com/patent/US9518341B2 ## CPC - D01D 5/08: Melt spinning methods {(D01D5/0023 takes precedence)} - D01F 6/66: from polyethers - D01F 6/74: from polycondensates of cyclic compounds, e.g. polyimides, polybenzimidazoles - D10B 2331/06: polyethers - Y10T 428/2913: Rod, strand, filament or fiber - D01D: MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS - D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS - D10B: INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract Provided are an amorphous polyetherimide fiber having not only a small single fiber fineness suitable for producing fabrics, and a fabric comprising the amorphous polyetherimide fiber. The fiber comprises an amorphous polyetherimide polymer having a molecular weight distribution (Mw/Mn) of less than 2.5, and having a shrinkage percentage under dry heat at 200° C. of 5% or less, and a single fiber fineness of 3.0 dtex or less. The fiber may have a tenacity at room temperature of 2.0 cN/dtex or greater. ## Claims ### Claim 1 A method for producing an amorphous polyetherimide fiber, the method comprising: melt-kneading an amorphous polyetherimide polymer having a molecular weight distribution (Mw/Mn) of less than 2.5 to obtain a molten polymer having a predetermined melt viscosity, discharging the molten polymer in a predetermined amount from a spinning nozzle having a single hole size of about 0.01 mm2 to about 0.07 mm2, and winding the discharged polymer at a predetermined winding rate without drawing to obtain an amorphous polyetherimide fiber having a tenacity at room temperature of 25° C. of 2.0 cN/dtex or greater, a shrinkage percentage under dry heat at 200° C. of 5% or less and a single fiber fineness of 3.0 dtex or less. ### Claim 2 (depends on 1) The method according to claim 1, wherein the winding rate is from 500 m/min to 4,000 m/min. ### Claim 3 (depends on 1) The method according to claim 1, wherein the polymer is discharged from a spinning nozzle at an amount of 35 to 300 g/min. ### Claim 4 (depends on 1) The method according to claim 1, wherein the polymer is discharged from a spinning nozzle at an amount of 35 to 300 g/min and the winding rate is from 500 m/min to 4,000 m/min. ### Claim 5 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer has a melt viscosity of 1,000 to 5,000 poise measured at a temperature of 390° C. and a shear rate of 1,200 sec−1. ### Claim 6 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer has a melt viscosity of 1,000 to 5,000 poise measured at a temperature of 390° C. and a shear rate of 1,200 sec−1, the polymer is discharged from a spinning nozzle at an amount of 35 to 300 g/min, and the winding rate is from 500 m/min to 4,000 m/min. ### Claim 7 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer is subjected to drying prior to melt-kneading at a temperature from 110° C. to 200° C. ### Claim 8 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer is subjected to drying prior to melt-kneading at a temperature from 110° C. to 200° C. under vacuum. ### Claim 9 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer is melt-kneaded with a metallic oxide. ### Claim 10 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer is melt-kneaded with a titanium oxide. ### Claim 11 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer is melt-kneaded with a thermal stabilizer. ### Claim 12 (depends on 1) The method according to claim 1, wherein the fiber is in a form of filament the production method causes fiber breakage at a frequency of 3 times or less per 100 kg of the polymer. ### Claim 13 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer is a polymer comprising an aliphatic, alicyclic, or aromatic ether unit and a cyclic de as a repeating unit. ### Claim 14 (depends on 13) The method according to claim 13, wherein, a main chain of the amorphous polyetherimide polymer comprises an aliphatic, alicyclic, or aromatic ester unit and an oxycarbonyl unit, other than the cyclic imide and the ether unit. ### Claim 15 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer has a weight-average molecular weight (Mw) of about 1,000 to about 80,000. ### Claim 16 (depends on 1) The method according to claim 1, wherein the tenacity at 25° C. of the amorphous polyetherimide fiber is from 2.3 to 4.0 cN/dtex. ### Claim 17 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide polymer has a melt viscosity of 1,500 to 4,000 poise measured at a temperature of 390° C. and a shear rate of 1,200 sec−1. ### Claim 18 (depends on 1) The method according to claim 1, wherein the single hole size of a nozzle is from 0.02 mm2 to 0.06 mm2. ### Claim 19 (depends on 1) The method according to claim 1, wherein the polymer is discharged from a spinning nozzle at the amount of from 40 to 280 g/min. ### Claim 20 (depends on 1) The method according to claim 1, wherein the amorphous polyetherimide fiber has a single fiber fineness of from 0.1 to 2.6 dtex.