POLYIMIDE PRECURSOR SOLUTION, METHOD FOR PRODUCING POLYIMIDE RESIN FILM, AND METHOD FOR PRODUCING SEPARATOR FOR LITHIUM ION SECONDARY BATTERY

1 . A polyimide precursor solution comprising:

a polyimide precursor;

an aqueous solvent containing a water-soluble organic solvent and water; and

particles,

wherein the particles have a volume average particle diameter within a range of 2.5 μm to 30 μm, an average circularity within a range of 0.900 to 0.990, and a standard deviation of circularity distribution of less than or equal to 0.1.

2 . The polyimide precursor solution according to claim 1 ,

wherein a content of the water is within a range of 50 mass % to 90 mass % based on the aqueous solvent.

3 . The polyimide precursor solution according to claim 1 ,

wherein the particles are within a range of 40 volume % to 80 volume % based on a total volume of a solid content of the polyimide precursor and the particles.

4 . The polyimide precursor solution according to claim 3 ,

wherein the particles are within a range of 50 volume % to 80 volume %.

5 . The polyimide precursor solution according to claim 1 ,

wherein the water-soluble organic solvent contains an organic amine compound.

6 . The polyimide precursor solution according to claim 5 ,

wherein the organic amine compound is a compound selected from the group consisting of triethylamine, N-alkylpiperidine, 2-dimethylaminoethanol, and a tertiary cyclic amine compound.

7 . The polyimide precursor solution according to claim 6 ,

wherein the tertiary cyclic amine compound is a morpholine compound.

8 . The polyimide precursor solution according to claim 7 ,

wherein the morpholine compound is N-methylmorpholine.

9 . The polyimide precursor solution according to claim 1 ,

wherein the particles are resin particles.

10 . The polyimide precursor solution according to claim 9 ,

wherein the resin particles are selected from the group consisting of styrene resin particles, (meth)acrylic resin particles, and polyester resin particles.

11 . The polyimide precursor solution according to claim 1 ,

wherein the standard deviation of the circularity distribution is less than or equal to 0.07.

12 . A method for producing a polyimide resin film, comprising:

coating a top of a substrate with the polyimide precursor solution according to claim 1 to form a coated film; and

drying the coated film to form a coat containing the polyimide precursor and the particles.

13 . The method for producing a polyimide resin film according to claim 12 , further comprising:

heating the coat produced by the method for producing a resin film according to claim 12 and imidizing the polyimide precursor contained in the coat to form a polyimide film; and

removing the particles.