METHOD OF MANUFACTURING LIGHT-RESISTANT POLYOXADIAZOLE FIBER OR THREAD Russian patent published in 2003 - IPC

FIELD: polymer production. SUBSTANCE: invention relates to manufacturing polyoxadiazole fibers or threads useful in metallurgy, chemical industry, and other areas for providing various heat-resistant products. Spinning solution is prepared at heating by charging concentrated sulfuric acid containing 17-65% free sulfuric anhydride, arylenedicarboxylic acid, hydrazine sulfate, m- and/or p-azabenzenedicarboxylic acid or their disodium or dipotassium salt(s), or mixture thereof with mineral acid salts. In particular, arylenedicarboxylic acid is terephthalic acid with 0.004-0.017% p-toluyl acid or mixture of terephthalic acid with 0.5 to 99% isophthalic acid with 0.04- 0.017% of mixture of p-toluyl acid with 0.5 to 99% m-toluyl acid. Heating is conducted gradually with intermediate formation of first 6.0-20% oligomer solution and then 5,0-14.18% oligomer solution followed by continuously or periodically performed polycondensation resulting in 3 to 14% solution of polymer in sulfuric acid. Solution is homogenized, filtered, and degassed. Spinning is carried out into sulfuric acid precipitation bath with density constituting 0.65- 0.83 that of spinning solution at 30-70 C. Thread travels during 2 to 17 sec and is stretched 2-6-fold in sulfuric acid solution. Threads are then subjected to heat treatment at 270-520 C for 2 to 900 sec being additionally stretched by 0.1-2%. EFFECT: improved physicochemical characteristics and oxygen index being resistant to light and showing high showing high color stability. 7 cl, 1 tbl, 7 ex