Patent ID: 8506864
Filing Date: 2013-08-13
Classification: B29C,B29K,C08J,D01D,D01F,Y10T

Abstract:
1. A process for the preparation of a multi-filament solid UHMW PO yarn having a tenacity of at least 27 g/d from slurries of UHMW PO comprising the steps of: a) forming a slurry of UHMW PO particles having an intrinsic viscosity measured in decalin at 135° C. of from 5 to 45 dl/g in a solvent for the UHMW PO at a first temperature which is below the temperature which said UHMW PO will dissolve in said solvent; b) processing said slurry through an extruder operating such that a mixture of said solvent and said UHMW PO is formed at a second temperature above the melting temperature of said UHMW PO, and the throughput rate of UHMW PO in said mixture is at least the quantity 2.5 D c) discharging said mixture from the extruder; d) passing said mixture through a heated vessel at a temperature above the melting temperature of said UHMW PO, said vessel having a volume such that the average residence time of the mixture in said vessel is from 2 to 120 minutes, whereby a homogeneous solution of said UHMW PO is formed having the UHMW PO dissolved in the solvent; e) passing the thus-formed solution out of said vessel and through a spinneret, said solution being at a temperature below the atmospheric boiling point of said solvent to form a multi-filament solution yarn; f) stretching the multi-filament solution yarn; g) cooling the multi-filament solution yarn to obtain a multi-filament gel yarn; h) stretching the multi-filament gel yarn; i) substantially removing the solvent from said multi-filament gel yarn to form a multi-filament solid yarn; and j) stretching the multi-filament solid yarn in one or more steps at temperatures from 25° C. to 165° C., whereby the resultant multi-filament solid yarn has a tenacity of at least 27 g/d.