| 摘要 |
A pre-oriented molded article of ultrahigh-molecular-weight polyethylene is composed of ultrahigh-molecular-weight polyethylene having an intrinsic viscosity of at least 5 dl/g, has a degree of orientation of at least 0.8, and has such a creep property that a stretched product of the molded article having a degree of orientation of about 0.97 shows an elongation of not more than 2% in an atmosphere at 80 DEG C. at 1000 seconds. The pre-oriented molded article is produced by (1) extruding a high-concentration molding solution composed of 15 to 80 parts by weight of ultrahigh-molecular-weight polyethylene and 85 to 20 parts by weight of a solvent capable of dissolving said polyethylene from a molding die at a temperature at which the molding solution remains a solution, (2) taking up the extrudate at a draft ratio of at least 3, and cooling the extrudate during or after take-up to crystallize the polyethylene in the extrudate and to form a pre-oriented molded article. A stretched molded article is produced from the pre-oriented molded article by (3) stretching the pre-oriented molded article at a stretch ratio of at least 3. |
