Metallocene Catalyst Composition for Wide-MWD Olefin Polymerization
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Solution Overview
Problem
Existing metallocene catalysts face challenges in achieving high activity and controlling the molecular weight and fine structure of olefin polymers, leading to narrow molecular weight distribution and limited control over polymer properties, which affects the durability and processability of polyolefin resins.
Innovation Solution
A novel metallocene compound with a specific chemical structure, represented by Chemical Formula 1-1 or 1-2, is used in a catalyst composition that includes a carrier and cocatalyst, enabling high catalytic activity and wide molecular weight distribution, resulting in olefin polymers with high short chain branching and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metallocene catalysts are used, then polymerization activity is maintained at acceptable levels, but catalyst stability is poor leading to frequent catalyst death and loss of activity
Solution Approach 1:
The patent employs a composite catalyst system combining a modified metallocene catalyst (with bulky substituents on the cyclopentadienyl rings) with a specific activator system. This composite approach enhances both stability and activity by synergistically combining the structural benefits of the modified metallocene with the activating effects of the co-catalyst system.
Solution Approach 2:
The patent modifies key parameters of the metallocene catalyst structure, specifically introducing bulky substituents at the 2-position of the cyclopentadienyl rings and adjusting the metal center electronic properties. These parameter changes optimize the balance between catalyst stability and polymerization activity.
2Duration of action of stationary object
If catalyst stability is improved through structural modification, then catalyst life is extended, but polymerization activity decreases
Solution Approach 1:
The patent introduces an intermediary activator system that mediates between the stable but less active modified metallocene catalyst and the requirement for high polymerization activity. The activator system activates the modified catalyst in a controlled manner, extending catalyst life while maintaining high activity through the intermediary interaction.
3Manufacturing precision
If conventional catalyst systems are used, then polymerization can proceed, but polymer microstructure control is insufficient and polydispersity index is high
Solution Approach 1:
The patent applies local quality modification by introducing bulky substituents at specific positions (2-position) of the cyclopentadienyl rings in the metallocene catalyst. This localized structural modification creates steric effects that control polymer microstructure and reduce polydispersity index without requiring complex overall catalyst system changes.
4Productivity
If catalyst activity is increased to improve productivity, then polymerization rate increases, but catalyst stability deteriorates and activity is lost rapidly
Solution Approach 1:
The patent creates a dynamic catalyst system where the modified metallocene catalyst and activator system work together in a controlled interaction. The bulky substituents on the metallocene provide structural stability while the activator system dynamically activates the catalyst sites, allowing high polymerization rates to be maintained without rapid catalyst deactivation.
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 novel metallocene compound enhances the catalytic activity and molecular weight distribution, producing olefin polymers with increased durability and mechanical strength by increasing tie-molecule content, thereby improving long-term durability and resistance to external impacts.
Implementation Method 1
a metallocene compound, which has a specific chemical structure, as a catalyst for producing a polyolefin polymer
Implementation Method 2
the polymerization of an olefin monomer to form a polyolefin polymer
Data Source
AI summary
This invention relates to a novel metallocene compound, a catalyst composition comprising the metallocene compound, and a method for preparing olefin polymer using the catalyst composition.