| 摘要 |
A method of extruding multi-filament polypropylene yarn in which the polypropylene is extruded at a temperature below 425 DEG F., such as in the range 415 DEG F. to 350 DEG F., particularly about 400 DEG F., into a hot zone having a temperature sufficiently high to retard cooling of the extruded polypropylene yarn. The temperature of the hot zone can be within 60 DEG F. of the temperature of extrusion. The yarn is then passed through a quenching zone across which air is blown to cool the yarn. The swell value of the polypropylene can be less than 3 and its melt flow may be greater than 30. The yarn is drawn down in the hot zone and the filaments may be drawn down to an undrawn denier of less than 40.
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