| 摘要 |
PURPOSE:To obtain the subject yarn having high strength and an elongation suitable to prevent the longitudinal cracking of the yarn by slitting a polypropylene film in the form of tape and subjecting the tape to two-stage drawing by roll-drawing and air-bath drawing under specific condition. CONSTITUTION:The objective excellent flat yarn having an elongation of 20-25% and resistant to longitudinal cracking can be produced by slitting a polypropylene film in the form of a tape, supplying the tape to the 1st-stage delivery rolls 1, 2, 3, a hot roll 4 maintained at 125-140 deg.C and the 1st-stage take-up rolls 5-9 to effect the 1st-stage drawing at a draw ratio of 5.5-7.0, keeping the drawn tape at >=140 deg.C and below the crystal melting point of polypropylene, introducing to the 2nd-stage delivery rolls 10, 11 having mirror- polished surface with maximum roughness of <=20mum, a hot-air bath 12 maintained at >=170 deg.C and the 2nd-stage take-up rolls 13-17 to effect the 2nd- stage drawing by an air-bath drawing process. |
