| 摘要 |
PURPOSE:To obtain a film-forming solution composed of a polyimide precursor and a specific mixed solvent, capable of giving a membrane having controllable porosity and pore size and excellent heat-resistance, chemical resistance and electrical properties and useful for the production of porous film, etc. CONSTITUTION:This film-forming solution is composed of (A) a polyimide precursor such as a precursor of poly(4,4'-oxydiphenylenepyromellitic imide) and (B) a mixed solvent consisting of >=3 kinds of poor solvents each of which can scarcely dissolve the precursor by itself, e.g. a mixed solvent of a water-soluble ether compound (e.g. THF), a water-soluble alcohol compound (e.g. methanol) and water. The porous film produced from the solution preferably has a gas permeability of >=0.1cm<3>/cm<2>.sec.cmHg and a dielectric constant of <3.0. |
