Process for preparing open structure fibers

Claim 1

A process for preparing open structure fiber which comprises extruding a fusion melt of acrylonitrile polymer and water through a spinnerette assembly which comprises in combination a. a spinnerette plate containing a plurality of orifices with a counterbore for each oriffice and b. removable pins positioned within each orifice-counterbore combination, each pin being of solid construction and having an upper portion positioned within said counterbore and a lower portion positioned within said orifice, said upper portion occupying a fixed position within said counterbore and enabling spinning composition to flow through the counterbore to the orifice at operative back pressure and said lower portion contacting the wall of the orifice at one position while providing clearance at other positions and having suitable shape characteristics to provide an open structure in the extrudate formed directly into a steam-pressurized solidification zone maintained under conditions of pressure and temperature which prevent formation of a sheath-core structure in the extrudate and enable orientation stretching of the extrudate to be achieved while said extrudate remains within said solidification zone.