Dual catalyst system for producing LLDPE and MDPE copolymers with long chain branching for film applications

US11339279B2 · kind B2 · utility

Assignee

• Chevron Phillips Chemical Company LP · US

Inventors

• Errun Ding · Bartlesville, US
• Chung Ching Tso · Bartlesville, US
• Max P. McDaniel · Bartlesville, US
• Ashish M. Sukhadia · Bartlesville, US
• Youlu Yu · Bartlesville, US
• Randall S. Muninger · Canton, US
• Aaron M. Osborn · Bartlesville, US
• Christopher E. Wittner · Bartlesville, US

Key dates

• Filing date: Apr 1, 2020
• Grant date: May 24, 2022
• Expiry date: Jul 23, 2040

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08L2207/066
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Disclosed herein are ethylene-based polymers generally characterized by a melt index of less than 15 g/10 min, a density from 0.91 to 0.945 g/cm3, a CY-a parameter at 190° C. from 0.2 to 0.6, an average number of long chain branches per 1,000,000 total carbon atoms of the polymer in a molecular weight range of 500,000 to 2,000,000 g/mol of less than 5, and a maximum ratio of ηE/3η at an extensional rate of 0.03 sec−1 in a range from 3 to 15. The ethylene polymers have substantially no long chain branching in the high molecular weight fraction of the polymer, but instead have significant long chain branching in the lower molecular weight fraction, such that polymer melt strength and bubble stability are maintained for the fabrication of blown films and other articles of manufacture. These ethylene polymers can be produced using a dual catalyst system containing a single atom bridged metallocene compound with an indenyl group and a cyclopentadienyl group, and an unbridged hafnium metallocene compound with two cyclopentadienyl groups.