Method of making polyimide fiber assembly

A method of making a polyimide fiber assembly comprising polyimide fibers comprising curved shapes with an average fiber diameter falling within a range of greater than 1 μm to not greater than 100 μm, said polyimide fiber assembly comprising a bulk density falling within a range of not less than 1 kg/m3 to not greater than 30 kg/m3, comprising the steps of:

• (i) discharging, through an orifice of a spinneret, a polymeric resin solution obtained by dissolving polyamic acid or polyimide in an organic solvent;
• and
• (ii) blowing gas onto the polymeric resin solution, which has been discharged through the orifice, from only one air nozzle from a single direction with respect to a direction of discharge of the polymeric resin solution so that the gas intersects with a flow of the polymeric resin solution, and using external force to cause the polymeric resin solution thus discharged through the orifice of a spinneret, to fly in a direction of the external force, the external force being external force of gas from a direction intersecting with a discharge direction in which the polymeric resin solution is discharged, and then forming a polymeric resin into fibers by spinning while vaporizing the organic solvent contained in the polymeric resin solution,
• the air nozzle and the orifice being provided separately without contacting each other,
• an angle between the discharge direction in which the polymeric resin solution is discharged and the direction of the gas from the air nozzle falling within a range of not less than 30 degrees to not greater than 150 degrees,
• a flow velocity of the gas that is discharged from the air nozzle is within a range of not less than 10 m/sec to not greater than 300 m/sec.