| 摘要 |
The present invention relates to a process for producing a pipe comprising at least one layer made of a polypropylene composition comprising a beta nucleated polypropylene base resin, wherein the process comprises the steps of:
a) extrusion of the polypropylene composition at a temperature of above 200 °C,
b) subsequent cooling of the extruded product with a cooling medium having a temperature of above 5 °C, and
c) subsequent annealing of the extruded product with an annealing medium having a temperature of at least the cooling medium temperature of step b),
and to a pipe comprising at least one layer made of a propylene polymer composition, wherein the average beta-crystallinity of the pipe layer, beta av is higher or equal to 20 %.
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