METHOD AND APPARATUS FOR MANUFACTURING CLAD PIPE FOR PLASTIC OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To obtain a clad pipe in which appearance of a wrinkle and a streak can be suppressed. SOLUTION: Molten PVDF (poly(vinylidene fluoride)) is extruded at ejection flow rate c (mm3/second) from a resin flow passage which is a clearance between an inner lip 70 and an outer lip 71. An inner lip outer peripheral surface radius is denoted by (a) (mm) and an outer lip inner peripheral surface radius is denoted by (b) (mm). The molten PVDF is sent to a sizing die 45 as a molten pipe 44. The molten pipe 44 solidifies while being molded to become a clad pipe in a cooling vacuum device 46. The clad pipe is taken out from the cooling vacuum device 46 at a taking-out speed (e) (mm/second). Arrangement is performed so that distance (d) (mm) between an extrusion die exit 43a and a sizing die entrance 45a satisfies a relation : [eäπ(b2-a2)}/c]-1≥0.1d. COPYRIGHT: (C)2005,JPO&NCIPI