Acrylic synthetic fiber and process for preparation thereof

Abstract

An acrylic synthetic fiber having in the transverse section thereof many openings having an indeterminate shape and a size of 0.1 to 1.6 .mu.m, wherein in the interior of the fiber, each opening forms a vein-like or straw-like void extending substantially in parallel to the longitudinal axis of the fiber and having a length of at least 60 .mu.m. This acrylic fiber is prepared by a) dissolving in a suitable solvent an acrylic polymer comprising at least 60 weight % of an acrylonitrile unit and 5 to 20 weight %, based on the weight of the acrylic polymer, of a polyalkylene glycol having a number average molecular weight of 5,000 to 50,000, b) aging the formed spinning solution for at least 4 hours, and c) extruding the spinning solution into a coagulating medium. The acrylic fiber is useful, e.g., as a frictional material comprising (a) a pulpy material made from the acrylic fiber, (b) a resin and (c) a filler.

Dependencies are inferred from the claim text.