HIGH-STRENGTH HIGH-MODULUS THERMAL-, FIRE-RESISTANT POLYIMIDE THREAD AND METHOD FOR PRODUCTION THEREOF Russian patent published in 2019 - IPC D01F6/74 C08G73/10 

FIELD: chemistry.

SUBSTANCE: invention relates to production of aromatic threads of polyimide nature. Method of producing yarn includes synthesis of initial polyamido acid (PAA) by polycondensation of aromatic diamines and dianhydrides of aromatic tetracarboxylic acids in medium of dimethylacetamide with simultaneous partial imidization of PAA, molding of intermediate PAA-thread and its final imidisation. Thread is formed by dry-wet or deep wet methods into water-dimethylacetamide precipitation bath with negative draw and positive plasticising stretches. Washed and dried partially imidised suture is subjected to final imidisation in a U-shaped heater at gradient-controlled increasing-decreasing temperatures.

EFFECT: obtaining polyimide fibres having a high level of mechanical and thermal properties, in particular a modulus of elasticity, specific breaking load, thermal stability and fire resistance.

6 cl, 1 dwg, 2 tbl, 6 ex