Process for forming an aramid copolymer

Abstract

The invention concerns processes for forming polymer crumb comprising residues of 2-(4-amino phenyl)-5 (6) amino benzimidazole (DAPBI), paraphenylene diamine (PPD), and terephthaloyl dichloride (TCl), comprising the steps of: i) forming a slurry of b mole percent DAPBI in a solvent system comprising organic solvent and c weight percent of an inorganic salt, wherein the inorganic salt is present in an amount of at least 5 weight present of the organic solvent; ii) contacting the slurry with a less than stoichiometric amount of terephthaloyl chloride to form an prepolymer solution; and iii) contacting the prepolymer solution with y mole percent of PPD and additional TCL to form a polymer solution; wherein the total amount of TCL added in steps ii) and iii) is a stoichiometric amount based on the total amount of DAPBI and PPD added in steps i) and iii); the DAPBI and PPD are added in an amount sufficient for providing a polymer solution having a weight percent solids of 12 percent or greater on a polymer basis; and wherein the sum of y+b is 100 and the product of b×c is 225 or greater.

Dependencies are inferred from the claim text.