Highly active β-nucleating additive for polypropylene
AssigneeTreofan Germany GmbH & Co. KG
InventorsDetlef Busch, Petra Häde, Bertram Schmitz
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Abstract
The invention relates to a method for enhancing the fraction of β-crystal modification in polypropylene by compounding nanocrystalline substances. A β-fraction of 50–100% is achieved with said method. The compounds are characterized by improved mechanical properties. The nanocrystalline powders can be directly compounded and compatibilized with surface-active substances in the PP matrix for better dispersion.
Claims20
Process for the preparation of polypropylene having an increased content of β-crystalline polypropylene, which comprises mixing nanoscale iron oxide and polypropylene to form a mixture and melting the mixture at a temperature of at least 150° C. and subsequently cooling in such a way that the cooled polypropylene melt has an increased content of β-crystalline polypropylene.
Process for the production of a biaxially stretched flat film, which comprises mixing nanoscale iron oxide and polypropylene to form a mixture and melting the mixture in an extruder at a temperature of at least 150° C. to form a melt, and extruding the melt through a flat-film die, and cooling the melt to give a pre-film in such a way that a content of at least 50% (measured by DSC) of β-crystalline polypropylene is formed, and warming the pre-film and stretching the pre-film in the longitudinal direction and cooling, subsequently re-warming and stretching in the transverse direction, and where the temperature during longitudinal stretching is selected in such a way that the β-crystalline polypropylene of the pre-film is converted into the alpha modification of polypropylene.
Dependencies are inferred from the claim text.