Patent ID: 6133406
Filing Date: 2000-10-17
Classification: C08G

Abstract:
A process for preparing an aromatic polyamide which comprises:(A) a dicarboxylic acid component unit comprising 30 to 100 mol % of a terephthalic acid component unit, and, as required, 0 to 70 mol % of a cyclic dicarboxylic acid component unit other than the terephthalic acid and, as required, 0 to 15 mol % of an aliphatic dicarboxylic acid having 7 to 20 carbon atoms; and(B) a diamine unit comprising 50 to 100 mol % of a component unit derived from an aliphatic alkylene diamine having 4 to 25 carbon atoms, and 0 to 50 mol % of a component unit derived from an alicyclic diamine having 3 to 25 carbon atoms; said process comprising:a step (i) of preparing a solid low-degree condensation product having an intrinsic viscosity .eta..sub.1 of from 0.05 to 0.2 dl/g by the polycondensation reaction of the dicarboxylic acid with the diamine;a step (ii) of solid-phase polymerizing said low-degree condensation product at a temperature of not higher than 195.degree. C. to prepare a solid-phase polymerized product having an intrinsic viscosity .eta..sub.2 satisfying the following relationship [I],.eta..sub.2 -.eta..sub.1 =0.02 to 0.1 dl/g [I]and;a step (iii) of further solid-phase polymerizing said solid-phase polymerized product, at a temperature of from 205 to 280.degree. C., to obtain an aromatic polyamide having an intrinsic viscosity .eta..sub.3 of from 0.15 to 1.1 dl/g and a ratio .eta..sub.3 /.eta..sub.2 of larger than 1.0.