Polyimide precursor-containing aqueous composition, method for producing polyimide film, and method for producing porous polyimide film

1. A polyimide precursor-containing aqueous composition, comprising:

at least one polymer material selected from the group consisting of a water-insoluble fibrous organic substance and a polyalkylene oxide having a viscosity-average molecular weight of 5 million or more;

a polyimide precursor;

particles; and

water,

wherein a content of the at least one polymer material is 0.05% by mass or more and 15% by mass or less with respect to the particles.

2. The polyimide precursor-containing aqueous composition according to claim 1 , wherein the content of the at least one polymer material is 0.5% by mass or more and 8.0% by mass or less with respect to the polyimide precursor.

3. The polyimide precursor-containing aqueous composition according to claim 2 , wherein the content of the at least one polymer material is 1.0% by mass or more and 3.0% by mass or less with respect to the polyimide precursor.

4. The polyimide precursor-containing aqueous composition according to claim 1 , wherein the polyalkylene oxide is a polyethylene oxide.

5. The polyimide precursor-containing aqueous composition according to claim 2 , wherein the polyalkylene oxide is a polyethylene oxide.

6. The polyimide precursor-containing aqueous composition according to claim 1 , wherein the polyalkylene oxide has a viscosity-average molecular weight of 6 million or more and 11 million or less.

7. The polyimide precursor-containing aqueous composition according to claim 1 , wherein a fiber diameter of the water-insoluble fibrous organic substance is 1 nm or more and 500 nm or less.

8. The polyimide precursor-containing aqueous composition according to claim 1 , wherein a fiber length of the water-insoluble fibrous organic substance is 10 nm or more and 10,000 nm or less.

9. The polyimide precursor-containing aqueous composition according to claim 1 , wherein the particles are resin particles.

10. The polyimide precursor-containing aqueous composition according to claim 9 , wherein the resin particles are particles containing a resin containing a structural unit derived from styrene.

11. The polyimide precursor-containing aqueous composition according to claim 1 , wherein a water content is 70% by mass or more with respect to a total mass of the polyimide precursor-containing aqueous composition.

12. The polyimide precursor-containing aqueous composition according to claim 1 , wherein a viscosity of the polyimide precursor-containing aqueous composition at 25° C. is 1 Pa·s or more and 200 Pa·s or less.

13. A method for producing a polyimide film, comprising:

applying the polyimide precursor-containing aqueous composition according to claim 1 onto a substrate to form a coating film;

drying the coating film to form a film containing at least one polymer material selected from the group consisting of the water-insoluble fibrous organic substance and the polyalkylene oxide having a viscosity-average molecular weight of 5 million or more, the polyimide precursor, and the particles; and

imidizing the polyimide precursor contained in the film to forint a polyimide film.

14. A method for producing a porous polyimide film, comprising:

applying the polyimide precursor-containing aqueous composition according to claim 1 onto a substrate to form a coating film;

drying the coating film to form a film containing at least one polymer material selected from the group consisting of the water-insoluble fibrous organic substance and the polyalkylene oxide having a viscosity-average molecular weight of 5 million or more, the polyimide precursor, and the particles;

imidizing the polyimide precursor contained in the film to form a polyimide film; and

removing the particles from the film or the polyimide film.