High tenacity polyethylene yarn
First Claim
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1. A process of producing a high strength polyethylene multi-filament yarn comprising the steps of:
- a) forming a slurry of an ultrahigh molecular weight polyethylene (UHMWPE) having an initial intrinsic viscosity (IV0) at least about 10 dl/g and an antioxidant in a solvent for said UHMWPE having an atmospheric pressure boiling point at least about 180°
C. at a temperature that is below the temperature at which the UHMWPE will dissolve in said solvent, the weight ratio of said UHMWPE to said solvent being from about 5;
95 to about 95;
5 and the weight ratio of said antioxidant to said solvent being from about 10 parts per million to about 1000 parts per million;
b) feeding said slurry to an intermeshing co-rotating twin screw extruder wherein the screws in said twin screw extruder are comprised of multiple segments having a root diameter of Dr millimeters, an outside diameter of Do millimeters, the ratio Dr/Do is R, the rotational speed of the screws is ω
revolutions per minute and following relationships are satisfied c) forming a liquid mixture in said extruder of said UHMWPE and said antioxidant, in said solvent at a temperature from about 140°
C. to about 320°
C., the intrinsic viscosity of the UHMWPE in said mixture being reduced to a value of from about 0.2 IV0 to about 0.7 IV0 in passing through said extruder d) passing said liquid mixture through a heated vessel at a temperature at least about 140°
C., said vessel having a volume such that the average residence time in said vessel is from about 2 to about 120 minutes, whereby a solution of the UHMVVPE is formed;
e) passing the thus-formed solution through a spinneret to form solution filaments;
f) passing said solution filaments from said spinneret through a short gaseous space into a liquid quench bath at a temperature less than about 35°
C. wherein said solution filaments are rapidly cooled to form gel filaments;
g) removing the solvent from the gel filaments to form solid filaments; and
h) stretching at least one of the solution filaments, the gel filaments and the solid filaments in one or more stages to a combined stretch ratio of at least about 10;
1, wherein a stretch of at least about 2;
1 is applied to the solid filaments to form a high strength multi-filament UHMWPE yarn, said UHMWPE yarn having a tenacity at least about 40 g/d, and having an intrinsic viscosity from 0.2 IV0 to 0.65 IV0.
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Abstract
A process for preparing ultra-high molecular weight polyethylene (UHMWPE) multi-filament yarns having improved tensile properties and the yarns and articles thereby produced.
32 Citations
20 Claims
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1. A process of producing a high strength polyethylene multi-filament yarn comprising the steps of:
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a) forming a slurry of an ultrahigh molecular weight polyethylene (UHMWPE) having an initial intrinsic viscosity (IV0) at least about 10 dl/g and an antioxidant in a solvent for said UHMWPE having an atmospheric pressure boiling point at least about 180°
C. at a temperature that is below the temperature at which the UHMWPE will dissolve in said solvent, the weight ratio of said UHMWPE to said solvent being from about 5;
95 to about 95;
5 and the weight ratio of said antioxidant to said solvent being from about 10 parts per million to about 1000 parts per million;b) feeding said slurry to an intermeshing co-rotating twin screw extruder wherein the screws in said twin screw extruder are comprised of multiple segments having a root diameter of Dr millimeters, an outside diameter of Do millimeters, the ratio Dr/Do is R, the rotational speed of the screws is ω
revolutions per minute and following relationships are satisfiedc) forming a liquid mixture in said extruder of said UHMWPE and said antioxidant, in said solvent at a temperature from about 140°
C. to about 320°
C., the intrinsic viscosity of the UHMWPE in said mixture being reduced to a value of from about 0.2 IV0 to about 0.7 IV0 in passing through said extruderd) passing said liquid mixture through a heated vessel at a temperature at least about 140°
C., said vessel having a volume such that the average residence time in said vessel is from about 2 to about 120 minutes, whereby a solution of the UHMVVPE is formed;e) passing the thus-formed solution through a spinneret to form solution filaments; f) passing said solution filaments from said spinneret through a short gaseous space into a liquid quench bath at a temperature less than about 35°
C. wherein said solution filaments are rapidly cooled to form gel filaments;g) removing the solvent from the gel filaments to form solid filaments; and h) stretching at least one of the solution filaments, the gel filaments and the solid filaments in one or more stages to a combined stretch ratio of at least about 10;
1, wherein a stretch of at least about 2;
1 is applied to the solid filaments to form a high strength multi-filament UHMWPE yarn, said UHMWPE yarn having a tenacity at least about 40 g/d, and having an intrinsic viscosity from 0.2 IV0 to 0.65 IV0.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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- 11. A high strength UHMWPE multi-filament yarn comprising at least about 100 filaments having a tenacity at least 40 g/d and an intrinsic viscosity less than or equal to about 16 dl/g.
- 16. A high strength UHMWPE multi-filament yarn comprising at least about 100 filaments having a tenacity at least about 45 g/d and an intrinsic viscosity less than or equal to about 16 dl/g.
Specification