Patent ID: 8497344
Filing Date: 2013-07-30
Classification: C08G

Abstract:
1. A method for obtaining an aromatic polyamide containing para-phenylene terephthalamide and 2-(p-phenylene)benzimidazole terephthalamide units, in the form of a crumb, by copolymerizing: i) a mole % of para-phenylenediamine; ii) b mole % of 5(6)-amino-2-(p-aminophenyl)benzimidazole; and iii) 90-110 mole % of terephthaloyl dichloride in a mixture of N-methyl pyrrolidone and containing c wt. % of calcium chloride, wherein c is within the range from 1 to 20, and wherein the ratio a:b ranges from 1:20 to 20:1, a+b is 100 mole %, and i), ii), and iii) together comprise 1-20 wt. % of the mixture, wherein the product b·c is at least 50 and less than 215 and the aromatic polyamide in the crumb has a relative viscosity ηrel of at least 4, wherein the crumb is defined as non-sticky particles at least 95% of which having an average diameter of 0.7-15 mm, and wherein the crumb is formed directly by the copolymerizing.