Propylene homopolymer having high melt strength and preparation method thereof

US9068030B2 · kind B2 · utility

Assignees

• CHINA PETROLEUM & CHEMICAL CORPORATION · CN
• BEIJING RESEARCH INSTITUTE OF CHEMICAL INDUSTRY, CHINA PETROLEUM & CHEMICAL CORPORATION · CN

Inventors

• Wenbo Song · Beijing, CN
• Meifang Guo · Beijing, CN
• Shijun Zhang · Beijing, CN
• Wenjun WEI · Beijing, CN
• Honghong Huang · Beijing, CN
• Luqiang Yu · Beijing, CN
• Tao Liu · Woodbury, US
• Huijie Hu · Beijing, CN
• Huan Xu · Beijing, CN
• Peiqian Yu · Beijing, CN
• Xiaomeng Zhang · Lo Wu, CN

Key dates

• Filing date: Jan 21, 2011
• Grant date: Jun 30, 2015
• Expiry date: Nov 30, 2031

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08F110/06
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The present invention provides a process for preparing high melt strength propylene polymer by direct polymerization, comprising that a propylene polymer with wide molecular weight distribution and containing “very high molecular weight fraction” can be prepared by controlling the species and ratios of the external electron donors in the Ziegler-Natta catalyst system at different reaction stages according to the requirement for different molecular weight fractions in the different propylene polymerization stage of the series operation, and said polymer has excellent mechanical properties, especially with very high melt strength. The present invention also provides a propylene homopolymer with high melt strength, comprising the following features: (1) the MFR is 0.2-10 g/10 min at 230° C. with a load of 2.16 kg; (2) the molecular weight distribution Mw/Mn is 6-20; (3) the content of the fraction with a molecular weight higher than 5,000,000 is higher than or equal to 0.8 wt %; (4) Mz+1/Mn is higher than or equal to 70. Said homopolymer can be used in the preparation of foam products, thermoforming products, biaxial stretching films, blown films and blow-molded products.