Silyl Ester Internal Donor for Broad Molecular Weight Distribution
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Solution Overview
Problem
Current Ziegler-Natta catalyst compositions for producing olefin-based polymers result in polymers with a narrow molecular weight distribution, which limits their versatility for diverse and sophisticated applications, necessitating the development of catalysts that can produce polymers with broader molecular weight distribution and improved properties.
Innovation Solution
Incorporation of silyl ester and silyl diol ester compounds into catalyst compositions, which act as internal electron donors, enabling the production of olefin-based polymers with broad molecular weight distribution and enhanced flexural modulus while maintaining high isotacticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional Ziegler-Natta catalyst compositions are used, then high catalytic activity and isotacticity are achieved, but the molecular weight distribution remains narrow
Solution Approach 1:
The patent changes the chemical parameters of the internal electron donor by using silyl ester compounds with specific structures (formula I) containing silicon atoms bonded to oxygen and ester groups. This parameter change in the donor structure broadens the molecular weight distribution while maintaining catalytic activity and isotacticity, resolving the contradiction between distribution breadth and catalyst simplicity.
Solution Approach 2:
The patent creates a composite catalyst system by combining magnesium halide support, titanium halide active sites, and silyl ester internal electron donors in a specific composite structure. This composite material approach enables broad molecular weight distribution while maintaining the functional integrity of each component, addressing the contradiction between versatility and complexity.
2Strength
If conventional internal electron donors are used, then catalyst activity is maintained, but flexural modulus and polymer properties are limited
Solution Approach 1:
The patent modifies the physical and chemical parameters of the internal electron donor by incorporating silyl ester groups with specific molecular structures. This parameter change enhances the flexural modulus of the resulting polymers while maintaining reasonable catalyst manufacturing complexity, as the silyl ester donors can be synthesized through standard organic chemistry procedures.
3Adaptability or versatility
If catalyst compositions are simplified, then ease of manufacture is improved, but molecular weight distribution breadth is reduced
Solution Approach 1:
The patent achieves broad molecular weight distribution by changing the molecular weight and structural parameters of the silyl ester internal electron donor. The donor structures with varying chain lengths and substituent groups (formula I) provide different steric and electronic environments, creating a broader distribution of polymer chain lengths while maintaining a relatively simple overall catalyst composition.
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 use of silyl ester and silyl diol ester-containing catalyst compositions results in olefin-based polymers with broader polydispersity index and greater flexural modulus compared to conventional catalysts, addressing the limitations of narrow molecular weight distribution and improving polymer properties.
Implementation Method 1
Incorporation of silyl ester and silyl diol ester compounds into catalyst compositions, which act as internal electron donors, enabling the production of olefin-based polymers with broad molecular weight distribution and enhanced flexural modulus while maintaining high isotacticity.
Data Source
AI summary
The present disclosure provides silyl esters and silyl diol esters suitable as internal electron donors in procatalysts for polymer production. Disclosed are procatalyst compositions formed from a procatalyst precursor and an internal electron donor that is a silyl ester or a silyl diol ester. The procatalyst compositions can be used with a cocatalyst and optionally an external electron donor and/or an activity limiting agent to form a Ziegler-Nana catalyst composition. The present catalyst compositions exhibit high catalyst activity and form olefin-based polymers with broad molecular weight distribution, favorable flexural modulus, and high isotacticity.