Process for spinning fibers of ionic thermoplastic polymers

Claim 1

An improved process for forming a fiber by passing a solution of a neutralized sulfonated thermoplastic polymer through a spinneret having a plurality of orifices, said sulfonated thermoplastic polymer having about 10 to about 100 meq. of neutralized sulfonate groups per 100 grams of said neutralized sulfonated thermoplastic polymer, said neutralized sulfonated thermoplastic polymer being formed from a thermoplastic polymer selected from the group consisting of polystyrene, poly-t-butyl-styrene, polychlorostyrene, polymethylstyrene and co- and terpolymers with acrylonitrile and vinyl toluene, a cation of said neutralized sulfonate groups being selected from the group consisting of aluminum, antimony, lead and Groups IA, IIA, IB and IIB of the Periodic Table of Elements, wherein the improvement consists essentially of dissolving said neutralized sulfonated thermoplastic polymer in a solvent system to form said solution, said solvent system being formed from a blend of a first solvent and a second solvent, said first solvent being an aromatic solvent which primarily solvates a hydrocarbon backbone of said neutralized sulfonated thermoplastic polymer, said second solvent being selected from the group consisting of C 1 to C 7 aliphatic and cycloaliphatic alcohols, said second solvent solvating ionic groups of said neutralized sulfonated thermoplastic polymer, said first solvent comprising about 60 to about 98 vol. % of said mixed solvent, said neutralized sulfonated thermoplastic polymer being at a concentration level of about 5 to about 50 grams per 100 ml. of said solvent system, said solution having a Brookfield viscosity at room temperature and 6 rpm. of about 1,000 to about 200,000 centipoises.