Polyamide film production method

摘要

The present invention provides a method for industrially stably producing a stretched polyamide film having uniform properties at a high speed. The polyamide film production method comprises the steps of: extruding a molten polyamide resin from a die into a sheet form on a rotary cooling roll having a roughened surface; pressing the sheet against the surface of the cooling roll with an air layer being present between the cooling roll and the sheet by blowing air onto the sheet from an air knife apparatus for cooling the sheet, the air layer having a widthwise thickness distribution such that an average air layer thickness Te in lateral edge regions of the sheet is greater than an average air layer thickness Tc in a middle region of the sheet; and biaxially stretching the sheet.