High strength polymetaphenylene isophthalamide fiber and process for producing the same

Abstract From the Canadian patent

A new high strength poly-m-phenylene isophthalamide fiber which comprises an m-phenylene isophthalamide polymer containing at least 95 molar% of recurring m-phenylene isophthalamide units and having an intrinsic viscosity of 0.7 to 2.5, a birefringence of 0.18 to 0.22 a degree of crystallinity of 45% to 55% a crystalline, size of 35 to 45 .ANG. a tensile strength of 6.5 g/d or more and a silk factor or 35 or more, is produced by wet-spinning a dope solution containing the polymer dissolved in an organic solvent, by carrying out a first adjustment of the content of the solvent in the wet-spun undrawn filament to a value of 15 to 30% by first wet, drawing the first content-adjusted filament …