| 摘要 |
PURPOSE:To obtain the subject tire cord having heat shrinkage characteristics comparable to those of rayon by melt spinning a polyester, then drawing the resultant yarn under specific conditions in many stages, subjecting the drawn yarn to relaxing heat treatment, subsequently performing plying treatment at a prescribed number of twists and further carrying out relaxing heat treatment. CONSTITUTION:A polyester having ethylene terephthalate as main recurring units is melt spun at >=6km/min spinning speed to provide spun yarn, which is then drawn under conditions of formulas I, II and III (DELTAn is the birefringence ratio; DR is the draw ratio; DT1 is the drawing temperature in the former period of drawing ; DT2 is the drawing temperature in the latter period of the drawing; Tg is the glass transition point of the polymer; Tm2 is the melting point of the polymer) and further subjected to relaxing heat treatment to afford drawn yarn having characteristics of 0.45-0.85 intrinsic viscosity, etc. The resultant drawn yarn is then plied at 1000-2800 twist coefficient to form a green cord. An adhesive is subsequently applied thereto and the resultant cord is subjected to relaxing treatment at 230-260 deg.C under conditions without causing drawing to provide the objective cord having 5-7.5% intermediate elongation. |
