Slot die for film manufacturing

A slot die comprising:

• a material distribution chamber configured to distribute a casting solution supplied to the material distribution chamber;
• and
• a lip in which a slot including an expansion portion is defined and through which the casting solution distributed in the material distribution chamber is discharged, wherein a width of the expansion portion taken along a first direction is expanded from one side of the expansion portion to a lip end facing the one side, and the one side of the expansion portion is apart from the lip end by a predetermined length taken along a second direction which is perpendicular to the first direction and substantially parallel to a flow direction of the casting solution, wherein the expansion portion of the lip includes width-directional wall surfaces, where the width-directional wall surfaces define the slot, and at least one of the width-directional wall surfaces is inclined with a predetermined inclination angle with respect to the second direction, and the predetermined inclination angle is greater than about 0 degree and equal to or smaller than about 10 degrees.