Aramid fibrils

Details Aramid fibrils Aramid fibrils

2004-11-30

2009-12-08

Gray, Jill (Department: 1794)

Stock material or miscellaneous articles

Coated or structually defined flake, particle, cell, strand,...

Staple length fiber

C428S357000, C428S395000, C264S140000, C264S142000, C264S183000, C162S157100, C162S157300

Reexamination Certificate

active

07629047

ABSTRACT:
Aramid fibrils having in the wet phase a Canadian Standard Freeness (CSF) value less than 100 ml, after drying a specific surface area (SSA) less than 7 m2/g, and a weight weighted length for particles having a length >250 μm (WL 0.25) less than 1.2 mm, are described. A method of preparing the fibrils includes the steps (a) polymerizing an aromatic diamine and an aromatic dicarboxylic acid halide to an aramid polymer, in a mixture of N-methylpyrrolidone or dimethylacetamide and calcium chloride or lithium chloride to obtain a dope wherein the polymer is dissolved in the mixture and the polymer concentration is 2 to 6 wt. %, (b) converting the dope to fibrils by using a jet spin nozzle under a gas stream, and (c) coagulating the fibrils using a coagulation jet.

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