| abstract |
A method for preparation of porous polyimide microparticles comprising, forming polyamide acid microparticles by pouring polymer solution prepared by dissolving polyamide acid containing 0.5 to 80 weight % of alkali metal salt to polyamide acid by 0.1 to 15 weight % concentration into a poor solvent selected from the group consisting of aliphatic solvents, alicyclic solvents, aromatic solvents, CS 2 and mixture of two or more these solvents and the temperature of which is adjusted to the range from −20° C. to 60° C., wherein particle size of said polyamide acid microparticles is adjusted to 50 nm to 10000 nm by controlling the temperature of said poor solvent, pore size of said polyamide acid microparticles is adjusted to the range from 20 nm to 500 nm and porosity of said polyamide acid microparticles is adjusted to the range from 0.1% to 30% by controlling a content or a kind of said alkali metal salt, then treating said polyamide acid microparticles by chemical imidation or thermal imidation, or by thermal imidation after chemical imidation so that the particle size distribution, pore size and porosity of said polyamide acid microparticles can be maintained. |