Solution spinning of UHMW poly (alpha-olefin) with recovery and recycling of volatile spinning solvent
First Claim
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1. 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;
f) 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 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.
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Abstract
A process for spinning high molecular weight poly (alph-olefin) filament, particularly ultrahigh molecular weight polyethylene filament, from solution in a volatile spinning solvent with recovery and recycling of the solvent.
35 Citations
17 Claims
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1. A process comprising the steps of:
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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;
f) 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 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A process comprising the steps of:
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a) forming a solution of a UHMW PE in a solvent comprising decalin, said UHMW PE 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 PE 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;
f) 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 sufficient to prevent the concentration of the evaporated solvent in a gas stream from being greater than the lower flammability limit of that solvent in air at 100°
C. as measured by ASTM E681-94. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification