METHOD OF PRODUCING HIGH-STRENGTH HIGH-MODULUS ARAMID THREADS (VERSIONS) Russian patent published in 2013 - IPC D01F6/60 

FIELD: chemistry.

SUBSTANCE: high-strength threads are obtained by a wet or dry-and-wet method of moulding an isotropic solution of an aromatic heterocyclic copolyamide in an organic solvent with leophilic salt additives, followed by washing, drying and heat treatment of the freshly moulded threads in a package under a vacuum and additional hot-stretching. Heat treatment is carried out in two steps: first under a vacuum of - 0.95 to -1.0 atm for 10-30 minutes, and the vacuum is reduced to - 0.75 to -0.9 atm and maintained until the end of the cycle; before hot-stretching, the threads are moistened to moisture content of 1.5-8.5%, said hot-stretching being carried out at temperature of 410-450°C. Heat treatment can also be carried out in a tubular heat chamber with gradient temperature distribution in the direction of movement of the thread from 30 to 500°C with a load of 0.05-0.5 cN/tex on the thread and oxygen content in the heat treatment zone of less than 1.5%. Air medium is fed by a stream which accompanies the movement of the thread at a speed which is at least twice as high as the speed of the thread.

EFFECT: high strength.

3 cl, 1 tbl, 28 ex