Stretching apparatus and method of manufacturing polyimide film using the same

A stretching apparatus comprising:

• an advancing mechanism for advancing a film;
• a take-in mechanism for taking in the film advanced from the advancing mechanism at a speed higher than a speed of the film advanced from the advancing mechanism;
• and
• two sets of film holding units placed at both end portions in a TD (Transverse Direction) of the film between the advancing mechanism and the take-in mechanism,
• wherein each of the film holding units has:
• a plurality of upper holding rollers placed in parallel at intervals in an MD (Machine Direction) of the film above a transfer path of the film;
• and
• a plurality of lower holding rollers placed opposite to the upper holding rollers below the transfer path of the film such that the plurality of lower holding rollers work together with the plurality of upper holding rollers to place the film sandwiched vertically between the rollers, and
• the upper holding rollers and the lower holding rollers are rotatably supported such that their rotational axes are inclined outward in the TD of the film toward downstream side of the MD of the film, and
• wherein when holding areas where the upper holding rollers hold the film in the MD of the film are considered, lengths, intervals, and inclination angles of rotational axes relative to the TD of the film of the upper holding rollers are set such that two adjacent holding areas are in contact with each other or overlap each other as viewed from the TD.