Polybenzazole fiber and method for production thereof

• US 5,993,963 A
• Filed: 09/30/1997
• Issued: 11/30/1999
• Est. Priority Date: 10/01/1996
• Status: Expired due to Fees

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Teramoto, Yoshihiko, Tanaka, Yoshikazu, Kitagawa, Tooru, Ishitobi, Michio
• Primary Examiner(s): Edwards, Newton
• Application Number:
  US08/940,780
• Time in Patent Office: 791 Days
• Field of Search: 428/357, 428/364, 428/394, 428/359
• US Class Current: 428/364
• CPC Class Codes: D01F 6/74 from polycondensates of cyclic compounds, e.g. polyimides, polybenzimidazoles
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2967 Synthetic resin or polymer

Abstract

A polybenzazole fiber characterized by having an elastic modulus of not less than 1350 g/d and requiring not longer than 10 minutes to reduce its water content from 2.0% to 1.5%, when determined using a thermogravimetric analyzer at 110° C. after moisture absorption of not less than 2.0% of a fiber, and a method for manufacturing such a polybenzazole fiber, comprising extruding a spinning dope comprising polybenzazole and a polyphosphoric acid from a spinneret to give a dope filament, and cooling the dope filament to not more than 50° C., followed by coagulation and washing. According to the method of the present invention, a polybenzazole fiber showing less decrease in strength by rapid heating can be provided.

Claims

1. A polybenzazole fiber characterized by having an elastic modulus of not less than 1350 g/d and requiring not longer than 10 minutes to reduce its water content from 2.0% to 1.5%, when the rate of loss in weight is determined using a thermogravimetric analyzer at 110°

C. after moisture absorption of not less than 2.0% of a fiber.

2. The polybenzazole fiber according to claim 1, wherein the elastic modulus is not less than 1400 g/d.

3. The polybenzazole fiber according to claim 1, wherein the elastic modulus is not less than 1500 g/d.

4. The polybenzazole fiber according to claim 1, wherein the elastic modulus is not less than 1600 g/d.

5. The polybenzazole fiber according to claim 1, wherein the fiber requires not longer than 8 minutes to reduce its water content from 2.0% to 1.5%.

6. The polybenzazole fiber according to claim 1, wherein the fiber requires not longer than 6 minutes to reduce its water content from 2.0% to 1.5%.