Novel Polypropylene Stabilization Method via Antioxidant Addition into Polymerization System

Abstract

Polypropylene stabilization by the additives addition without pelletizing process makes it possible to save production energy effectively, because the pelletizing process consumes one-third of total production energy. An addition of stabilizer into polymerization system was studied as a novel method to stabilize polypropylene. Since the Ziegler-Natta catalyst is known to be deactivated by polar groups of stabilizer, aluminum phenoxide (Al-Ph) was prepared via the reaction of phenolic antioxidant, 3 (3, 5-di-t-butyl-4-hydroxylphenyl)-N-octadecylpropionamide (AO-1) with triethylaluminum in order to mask the polar groups such as OH group of AO-1. Propylene polymerization was carried out in the presence of the AO-1 or its Al-Ph. Although the AO-1 gave rise to decrease in catalyst yield and change in hydrogen response, the Al-Ph of AO-1 had no influence on the catalytic polymerization behavior and thus the obtained polymer characteristics such as molecular weight, polydispersity and meso pentad as a stereoregularity were comparable to that polymerized without the antioxidant and the aluminum aryloxide of AO-1. Polypro pylene obtained in the presence of the aluminum aryloxide was well stabilized for oxidation and its stability was over 1000h at 100°C.