PROCEDURE FOR PRODUCION OF POLY-OXADIAZOLE FIBRE OR THREAD Russian patent published in 2010 - IPC D01F6/74 

FIELD: machine building.

SUBSTANCE: spinning solution is produced with successive loading oleum at 10-40°C, with adding arylene-dicarbonic acid and hydrazine-sulphate containing 0.1-1.0% of sulphuric acid at weight ratio of free sulphuric anhydride in oleum, arylene-dicarbonic acid and hydrazine-sulphate 1.2-1.4:1.0:0.79-1.0 correspondingly. Total contents of sulphuric anhydride in oleum are not less, than 84.6%. Continuously stirred mixture is heated to 40-100°C and conditioned at this temperature till solution of oligomer of specific viscosity of 0.1-0.3 is obtained. Mixture is cooled to temperature not exceeding 40°C, oleum of 10-40°C temperature is additionally introduced, and ratio of free sulphuric anhydride in oleum to arylene-dicarbonic acid is 1.4-1.8:1. Further the procedure consists in mixing, in poly-condensation by holding at 80-160°C till specific viscosity 1.5-4.0 is achieved and in diluting poly-condensate solution with sulphuric acid. Successively solution is homogenised, filtered and degassed. Sedimentation is carried out at 25-80°C in a settling bath, where contents of total sulphuric anhydride are 25-50%. Additionally sodium sulphate, or ammonium, or zinc or their mixture at amount of from 0.5 g/l to 300 g/l is added into the bath. Further formed fibre or thread is stretched, pressed and washed. Formed fibre or thread is neutralised to pH 8.5-9.5 with water solution of sodium bicarbonate or potassium bicarbonate, or sodium carbonate or their mixture, or water solution of sodium hydroxide. Finally fibre or thread is heat-treated.

EFFECT: fibres or threads possess increased resistance to hydrolysis and fire, and upgraded elastic properties.

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