Patent ID: 8362192

Claim:
A method for obtaining an aromatic polyamide crumb from an aromatic diamine and an aromatic diacid chloride, which aromatic polyamide comprises 5(6)-amino-2-(p-aminophenyl)benzimidazole terephthalamide units and has a relative viscosity η rel of at least 3, comprising: adding at least monomers (i)-(iii) in N-methyl pyrrolidone as solvent wherein: i) is 0-30 mole % para-phenylenediamine (PPD); ii) is 20-50 mole % 5(6)-amino-2-(p-aminophenyl)benzimidazole (DABPI); iii) is 49.05-50.05 mole % terephthaloyl dichloride (TDC); and optionally calcium chloride to obtain a CaCl 2 /aromatic diamine molar ratio less than 0.5, and an aromatic diamine/aromatic diacid chloride ratio between 0.99 and 1.01; mixing the monomers and the optional calcium chloride to a homogeneous mixture having a monomer concentration of 5 to 12 wt %, followed by adding calcium chloride to the homogeneous mixture to obtain a CaCl 2 /aromatic diamine molar ratio of 0.6-1.0; and polymerizing the mixture in a reactor having a measure capacity of at least 160 L, wherein mole % relates to the molar percentage of the monomers with regard to the total of aromatic diamine and aromatic diacid chloride monomers.