| 摘要 |
The process for continuous manufacture of the said products is characterised by a) melting the partially crystalline thermoplastics in an extruder under a pressure of at least 300 - 10,000 bar, preferably 400 - 2,000 bar, to a material temperature which is at least 20, preferably at least 30 degrees higher than the melting temperature of the thermoplastic, then b) introducing the polymer melt into an orientation zone, in which the cross-section of the material stream reduces continuously, the angle between the longitudinal axis of the extruder and the cross-sectional reduction being less than 45 DEG , preferably less than 30 DEG , then c) cooling the polymer melt while maintaining the high pressure of 300 - 10,000, preferably 400 - 2,000 bar in a first cooling zone A1 in stages or continuously for a temperature below the crystalline melting point or above the Vicat softening point of the partially crystalline polymer used, moulding into the final shape, then d) cooling the polymer material in a second cooling zone A2 without further forming to a temperature below the Vicat softening point of the polymer used, then e) applying a taking-off force to the extrudate emerging from the extruder die, said force being sufficient to overcome the friction occurring between the first cooling zone and second cooling zone as well as within the second cooling zone A2, without the internal pressure prevailing in the extruder dropping below 300 - 10,000, preferably 400 to 2,000 bar, and without the shape of the extrudate undergoing any change thereby. |
