Patent ID: 9394638
Filing Date: 2016-07-19
CPC Classification: D01D,D01F,D04H,Y10T

Claim Text:
1. A process for producing a non-woven fabric, comprising the steps of: preparing a polyamic acid by polycondensation of reactants consisting of an aromatic tetracarboxylic acid anhydride and an aromatic diamine having a benzoxazole structure in one or more organic solvents, and electro-spinning the polyamic acid to form a polyimide precursor fiber bundle; and imidizing the polyimide precursor fiber bundle to obtain the non-woven fabric having a fiber diameter in the range of 0.001 μm to 100 nm and having a coefficient of linear expansion in the range of −6 ppm/° C. to 14 ppm/° C.; wherein the aromatic tetracarboxylic acid anhydride is selected from the group consisting of the aromatic diamine is selected from the group consisting of: the polyamic acid has a reduced viscosity of 3.0 dl/g or more, and the electro-spinning is carried out under the following conditions: