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US 5,686,033 AGranted
Process of making PTFE fibers
AssigneeHitachi Cable, Ltd.
InventorMasazumi Shimizu
Life of this patent
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Abstract
The present invention provides high strength fiber of polytetrafluoroethylene (PTFE) having a strength of at least 0.5 GPa, which is manufactured by forming a monofilament of PTFE group polymer by paste extrusion, free end annealing the monofilament, and subsequently drawing the annealed monofilament to form the fiber, wherein PTFE molecular chains are oriented in a direction parallel to an axial direction of the fiber.
Claims19
A method for manufacturing high strength fiber of polytetrafluoroethylene comprising the steps of;
- paste-extruding a billet of polytetrafluoroethylene group polymer to form a monofilament,
- free end annealing said monofilament,
- cooling gradually said annealed monofilament, and
- drawing said annealed monofilament to form a fiber.
1 more element
A method for manufacturing high strength fiber of polytetrafluoroethylene comprising the steps of;
- paste-extruding a billet of polytetrafluoroethylene group polymer at a temperature equals to or higher than 30.degree. C. with a reduction ratio at least 300 to form a monofilament of 0.5 mm diameter,
- free end annealing said monofilament at a temperature equals to or higher than 340.degree. C.,
- cooling gradually said annealed monofilament with a cooling speed equals to or slower than 5.degree. C./min.,
- drawing said annealed monofilament at least 50 times at a temperature equal to or higher than 340.degree. C. with a drawing speed of at least 50 mm/sec to form a fiber of 50 .mu.m diameter, and
- cooling the fiber immediately after the drawing.
2 more elements
Dependencies are inferred from the claim text.