Ziegatta Catalyst Diester Donor for High Melt Flow Propylene
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Solution Overview
Problem
Current Ziegler-Natta catalyst compositions for olefin polymerization do not consistently produce propylene-based polymers with high melt flow rate, high isotacticity, and high catalyst activity, limiting the variability and performance of olefin-based polymers for emerging applications.
Innovation Solution
Incorporating a 3,6-di-substituted-1,2-phenylene aromatic diester as an internal electron donor in catalyst compositions, along with a magnesium and titanium moiety, and maintaining a specific hydrogen-to-propylene mole ratio during polymerization to enhance catalyst activity and produce propylene-based polymers with high melt flow rate and isotacticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional Ziegler-Natta catalyst compositions are used for olefin polymerization, then catalyst activity and selectivity are improved, but the melt flow rate of the produced propylene-based polymer is limited
Solution Approach 1:
The patent changes the chemical structure parameters of the internal electron donor from conventional options to specifically 3,6-di-substituted-1,2-phenylene aromatic diesters with particular substitution patterns (R1-R14 groups). This structural parameter change enables the catalyst to achieve both high activity and high melt flow rate simultaneously by modifying how the catalyst interacts with propylene monomers and responds to hydrogen chain transfer agents.
Solution Approach 2:
The patent creates a composite catalyst system combining magnesium support, titanium active centers, 3,6-di-substituted-1,2-phenylene aromatic diester internal electron donor, and external electron donors. This composite structure synergistically combines the functions of each component to achieve high catalyst activity, high isotacticity, and high melt flow rate that cannot be achieved by single components alone.
2Manufacturing precision
If conventional internal electron donors are used in Ziegler-Natta catalysts, then high isotacticity is achieved, but the hydrogen response and melt flow rate are insufficient
Solution Approach 1:
The patent modifies the substitution parameters at positions R1-R14 of the phenylene diester structure to optimize the balance between isotacticity control and hydrogen response. Specific substitution patterns (such as methyl, ethyl, vinyl groups at R1 and R4; secondary or tertiary alkyl groups at R2 and R3) are designed to create appropriate steric and electronic environments that enable both high isotacticity and enhanced hydrogen chain transfer capability.
Solution Approach 2:
The patent designs the catalyst system to be dynamically responsive to hydrogen concentration changes in the polymerization medium. The 3,6-di-substituted-1,2-phenylene aromatic diester structure enables the catalyst to adjust its chain transfer behavior in response to varying hydrogen levels, allowing optimization of both isotacticity and melt flow rate based on process conditions.
3Ease of operation
If high melt flow rate propylene-based polymer is produced, then processing flexibility is improved, but catalyst activity and isotacticity may be compromised
Solution Approach 1:
The patent employs a multi-component composite catalyst system where magnesium support provides structural stability, titanium centers provide active polymerization sites, 3,6-di-substituted-1,2-phenylene aromatic diester provides stereoselectivity and hydrogen response, and external electron donors fine-tune catalyst behavior. This composite structure ensures consistent high performance across different operating conditions while maintaining high melt flow rate.
Solution Approach 2:
The 3,6-di-substituted-1,2-phenylene aromatic diester internal electron donor performs multiple functions simultaneously: it provides steric control for high isotacticity, enables high hydrogen response for high melt flow rate, and maintains catalyst stability. This multi-functionality allows the catalyst to consistently deliver high performance across varying process conditions without compromising reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process results in catalyst compositions with high hydrogen response, producing propylene-based polymers with broad molecular weight distribution and extremely high melt flow rates without requiring peroxide cracking, thereby improving polymerization efficiency and product properties.
Implementation Method 1
Known is the incorporation of substituted phenylene aromatic diester as an internal electron donor in olefin polymerization catalyst compositions. In particular, the internal electron donor, 5-tert-butyl-3-methyl-1,2-phenylene dibenzoate in Ziegler-Natta catalyst compositions, contributes to high catalyst activity and high selectivity during polymerization
Implementation Method 2
contacting, under polymerization conditions and in the presence of hydrogen (H2), propylene and optionally one or more comonomers with a catalyst composition. The process further includes maintaining a H2/propylene mole ratio greater than or equal to 0.005 during the contacting; and forming a propylene-based polymer having a melt flow rate greater than 10 g/10 min
Data Source
AI summary
Disclosed are catalyst compositions having an internal electron donor which includes a 3,6-di-substituted-1,2-phenylene aromatic diester. Ziegler-Natta catalyst compositions containing the present catalyst compositions exhibit very high hydrogen response, high activity, high selectivity and produce propylene-based olefins with high melt flow rate.