Mixed PTFE powder and a high density multi expanded (HDME) PTFE yarn with excellent tensile strength using the PTFE powder, and methods of preparing the same

摘要

A mixed PTFE powder according to the present invention is prepared by the steps of preparing a PTFE mixed dispersion by dispersing MoS₂, Al₂O₃, and Al(OH)₃ in a PTFE emulsion; dehydrating the PTFE mixed dispersion by adding Na₂CO₃ into the PTFE mixed dispersion to form a cake type compound; preparing an ingot by drying the cake type compound for about 16 to 24 hours at the temperature of about 120 to 190° C.; and pulverizing the ingot in a 30-35 mesh vibrating net. An HDME PTFE yarn according to the present invention is prepared by the steps of preparing the mixed PTFE powder; adding kerosene of about 18 to 25 wt. % as solvent to the mixed PTFE powder and maintaining the resultant for about 40 to 50 hours at the temperature of about 30 to 50° C.; extruding the resulting mixed PTFE into the form of rod at about 70 to 90° C.; calendering the rod into the form of sheet at about 100 to 150° C., the width of the sheet being about 100 to 300 mm and the thickness about 0.3 to 0.7 mm; folding the sheet to become a three layered sheet and passing through the three layered sheet in an oven of about 250 to 270° C. at a speed of about 10 to 40 cm per second; and drawing the three-layered sheet at the temperature of about 450 to 500° C. at the speed of about 30 to 100 cm/s and the drawing ratio of about 200 to 600%.