METHOD OF POLYIMIDE FILM PRODUCING Russian patent published in 1996 - IPC

FIELD: chemical technology, polymers. SUBSTANCE: invention involves polyamidoacid solution pouring on backing, polyamidoacid film drying and its by-stage thermic working at stressed state. The first stage is carried out at constant size and step-by-step temperature elevation from 100 to 400 C. Thermic working at the second stage is carried out on cylindric gaseous cushion at force 0.1-0.5 kg/cm² without film fixation at transverse direction at 320-440 C. Site noncontacting with gaseous cushion is blown with gas at 320-440 C under pressure less than of gas pressure in cushion, not less than by 5-10%. Then film under extension condition is cooled and gas consumption is calculated from value H/h where H - gaseous cushion thickness at middle between inlet and outlet of film from thermic working site, h - gaseous cushion thickness at inlet and outlet of film from thermic working site. Produced polyimide film is used in electronic engineering and electrotechnics as a base for magnetic bands. EFFECT: improved method of film producing. 3 dwg, 1 tbl