Film manufacturing method, film manufacturing device, and jig

1. A film manufacturing method using a film manufacturing apparatus,

the film manufacturing apparatus including:

an extrusion die having a feed opening for supplying a resin and a lip opening for ejecting the supplied resin in a form of a film;

the extrusion die having opposing lip edges defining a width of the lip opening;

an end plate which is provided at each end in a longer side direction of the lip opening of the extrusion die and serves as a sidewall of the lip opening;

a seal part which is provided between the extrusion die and the end plate and having a seal part end surface, wherein the seal part end surface, opposing lip edges of the extrusion die and the end plate at the lip opening are not flush with each other, thereby providing a gap between the opposing lip edges of the extrusion die and the end plate at the lip opening; and

a jig movably mounted on the end plate so as to cover the gap between the opposing lip edges of the extrusion die and the end plate at the lip opening and to not cover the opposing lip edges of the extrusion die,

said film manufacturing method comprising:

an extrusion step of, in a state in which the jig is mounted on the end plate so as to cover the gap between the opposing lip edges of the extrusion die and the end plate at the lip opening and to not cover the opposing lip edges of the extrusion die, extruding the resin from the lip opening so as to form the film.

2. The film manufacturing method as set forth in claim 1 , wherein the jig has a tip that faces the extrusion die, the tip being located at the opposing lip edges of the extrusion die.

3. The film manufacturing method as set forth in claim 1 , wherein the jig has a first outer surface that faces the end plate and a second outer surface that is opposite to the first outer surface and has a rounded part so as to be closer to the lip opening, the rounded part having a radius of curvature R of more than 0 mm and not more than 10 mm.

4. The film manufacturing method as set forth in claim 1 , wherein the jig has a tip that faces the lip opening, the tip having a width that is not less than a length in a shorter side direction of the lip opening and not more than 10 mm.

5. The film manufacturing method as set forth in claim 1 , wherein the resin is at least one resin selected from the group consisting of a polyimide solution, a polyamide imide solution, and a polyamide acid solution which is a precursor of polyimide.

6. The film manufacturing method as set forth in claim 5 , wherein:

the resin is the polyamide acid solution which is a precursor of polyimide; and

the polyamide acid solution contains a chemical imidization agent.

7. The film manufacturing method as set forth in claim 1 , wherein:

the extrusion die has a plurality of resin flow paths from the feed opening to the lip opening; and

in the extrusion step, a multilayer resin film is formed by supplying the resin separately to each of the plurality of resin flow paths, causing the separately supplied resin to flow together, and ejecting the resin from the lip opening.

8. The film manufacturing method as set forth in claim 1 , wherein:

the extrusion die has three resin flow paths from the feed opening to the lip opening; and

in the extrusion step, a resin film having a three-layer structure is formed by supplying, to one of the three resin flow paths which one is inner than the other two resin flow paths, a polyamide acid solution which is a precursor of non-thermoplastic polyimide, and by supplying, to the other two resin flow paths which are outer than the one of the three resin flow paths, a polyamide acid solution which is a precursor of thermoplastic polyimide.