Abstract text

Provided is an air injection nozzle, which is used for a heat treatment such as the heating, cooling or thermal insulation of a running sheet (or film) with injected air. In the air injection face, a number of air injection holes are so arrayed at an interval (Py) in first and second rows that the air injection holes of a first row and the air injection holes of a second row are staggered. The first row and the second row are positioned at an interval (Px). The air injection face and the sheet running face confront each other at a distance (L). The air injection holes in the air injection face have a diameter (D). The interval (Px), the interval (Py), the distance (L) and the diameter (D) satisfy Formula (1): 6≦(L/D)/(Px/Py)≦9, and Formula (2): 4≦L/D≦8. This air injection nozzle is employed as a resin film heat treating apparatus in a tenter oven to be used for manufacturing the resin film.