POLYTETRAFLUOROETHYLENE FIBER

PROBLEM TO BE SOLVED: To provide PTFE (polytetrafluoroethylene) fiber adapted to be sewn at high speeds. SOLUTION: Provided is the PTFE fiber, wherein the fiber has at least about 0.36 g/d of toughness. The toughness is in a range of about 0.36-1.01 g/d, preferably about 0.50-0.80 g/d, the most preferable toughness is about 0.60 g/d. The fiber has a peak engineering stress greater than about 1.6 g/d and a break strain greater than about 15.5%. A preferred range for the peak engineering stress is from about 3.0 g/d to about 5.0 g/d, and a preferred range for the break strain is from about 20% to about 50%. Most preferably, the peak engineering stress is about 4.4 g/d, and the break strain is about 24%. In another aspect, the invention provides a process for making a fiber that involves providing a PTFE fiber and heating the PTFE fiber to a temperature of from about 300°C to about 500°C, while overfeeding the PTFE fiber at an overfeed of not more than about 70%. A preferred temperature range is from about 350°C to about 450°C, and a preferred overfeed range in the overfeeding step is from abut 10% to about 20%. Most preferably, the temperature in the heating step is about 400°C and the overfeed in the overfeeding step is about 15%. The PTFE fiber may be used as a filament for an improved dental floss, and is also suited for an improved bearing material. COPYRIGHT: (C)2010,JPO&INPIT