Propylene polymer with improved processability in thermoforming

摘要

The present invention concerns a propylene polymer comprising at least two propylene polymer fractions of different melt flow index and a minor amount of at least one comonomer, said propylene polymer being further characterized by specific ranges for melt flow index, xylene solubles content and recovery compliance. Said propylene polymer is particularly suited for thermoforming. The present invention further concerns a process for producing said propylene polymer as well as its use in thermoforming.

主权项

1. A propylene polymer comprising at least one comonomer and at least two propylene polymer fractions of different melt flow index, said propylene polymer being characterized by
a melt flow index ranging from 0.5 dg/min to 8.0 dg/min, determined according to ISO 1133, condition L at 230° C. and 2.16 kg, a xylene solubles content ranging from 1.0 wt % to 4.0 wt %, relative to a total weight of the propylene polymer, and a total comonomer content of from 0.1 wt % to 1.0 wt %, relative to the total weight of the propylene polymer, wherein the fraction with the lowest melt flow index has a melt flow index ranging from 0.2 dg/min to 1.0 dg/min, determined according to ISO 1133, condition L at 230° C. and 2.16 kg; wherein each of the at least two propylene polymer fractions has substantially the same comonomer content and, relative to the comonomer content of the propylene polymer fraction with the lowest melt flow index, the comonomer content of the other propylene polymer fraction is from 70% to 130%, under the provision that each of the at least two propylene polymer fractions comprises comonomer.