ARAMID MICROFIBERS, METHOD FOR PRODUCING SAME, AQUEOUS ARAMID FIBER DISPERSION, NONWOVEN FABRIC, SEPARATOR FOR SECONDARY BATTERIES, AND SECONDARY BATTERY

摘要

The present invention provides aramid fibers which enable the achievement of an aqueous dispersion that is capable of forming a multilayer body wherein: a nonwoven fabric layer is easy to be uniform; and high adhesion is achieved between the nonwoven fabric layer and a porous base material without a binder.　Aramid microfibers according to the present disclosure have an average fiber length of from 10 μm to 200 μm; the viscosity η1 (at 25°C, at a shear rate of 10 s-1) of a 1% by mass aqueous dispersion thereof is from 500 mPa to 5,000 mPa; the viscosity η2 (at 25°C, at a shear rate of 1 s-1) of a 1% by mass aqueous dispersion thereof is from 10,000 mPa to 70,000 mPa; and the ratio of η2 to η1, namely (η2/η1) is from 14 to 25.　A method for producing aramid microfibers according to the present disclosure obtains aramid microfibers set forth in claim 1 by subjecting aramid fibers having an average fiber of from 200 μm to 1,000 μm to a heat treatment with use of an alkaline aqueous solution, and subsequently subjecting the aramid fibers to a fibrillation treatment.