Patent ID: RE41268

Claim:
A process comprising the steps of: a) forming a solution of a UHMW PO in a solvent, said solvent comprising cis-decahydronaphthalene, trans-decahydronaphthalene or mixtures of cis-and trans-decachydronaphthalene, said UHMW PO having an intrinsic viscosity in decalin at 135° C. of from 5 dl/g to 35 dl/g, said solvent having an atmospheric pressure boiling point of from 125° C. to 250° C.; b) spinning the solution through a spinneret at a temperature between 115° C. and the atmospheric pressure boiling point of said solvent to form a solution filament; c) cooling the solution filament to a temperature below the gelation temperature to form a gel filament; d) evaporating said solvent from the gel filament and optionally from the solution filament into one or more gas streams to form a dried filament, the evaporation continuing until the solvent concentration in the dried filament is less than 5 percent by weight of UHMW PO plus solvent; e) stretching at least one of the solution filament, the gel filament and the dried filament to a combined stretch ratio of at least 10:1, wherein at least 2:1 of the combined stretch is of the dried filament; and f) recovering solvent for reuse by separating at least 90% of said solvent from the gas stream(s) by condensation; g) recycling said solvent to the solution forming device; and h) recycling the gas streams; wherein at least 95% of said solvent is recycled; wherein the volumetric flows of the gas streams are sufficent sufficient to prevent the concentration of the evaporated solvent in a gas stream from from being greater than the lower flammability limit of that solvent in air at 100° C. as measured by ASTM E681-94.