Bridged Metallocene Catalyst Comonomer Incorporation
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Solution Overview
Problem
Current catalyst systems for polyolefin production face inefficiencies in comonomer incorporation, particularly in the production of low-density resins, leading to higher production costs and limitations in forming copolymers with desirable properties.
Innovation Solution
The development of new catalyst compositions involving tightly-bridged ansa-metallocene compounds, activators, and optional organoaluminum compounds, which enhance comonomer incorporation and activity, allowing for the production of low-density polyolefins with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional catalyst systems are used for polyolefin production, then production costs are reduced and manufacturing is simplified, but comonomer incorporation efficiency is poor and copolymer property range is limited
Solution Approach 1:
The catalyst system is segmented into distinct functional components: a metallocene compound with specific ligand structures, an organoaluminum activator, and an optional organoboron compound. Each component performs a specific function in enabling high comonomer incorporation, allowing optimization of individual elements to achieve overall system effectiveness without unnecessary complexity.
Solution Approach 2:
The patent employs specific parameter ranges for catalyst components including metallocene ligand structures (cyclopentadienyl and indenyl types), organoaluminum compound ratios (1:10 to 10:1 Al:metallocene), and organoboron compound concentrations. These parameter optimizations enable high comonomer incorporation efficiency while maintaining manageable catalyst system complexity.
2Productivity
If tightly-bridged ansa-metallocene compounds with activators are used, then comonomer incorporation rates increase and low-density polyolefin properties are improved, but catalyst composition complexity increases
Solution Approach 1:
The metallocene compound is pre-associated with the organoaluminum activator and optional organoboron compound to form a pre-formed catalyst composition before polymerization. This preliminary association ensures optimal activation and comonomer incorporation capability is established beforehand, maximizing productivity during the actual polymerization process.
Solution Approach 2:
The catalyst system uses a composite structure combining metallocene compounds (with specific ligand combinations), organoaluminum compounds, and organoboron compounds. This composite catalyst composition synergistically enhances comonomer incorporation rates and enables production of low-density polyolefins with tailored properties while managing the complexity through defined component relationships.
3Adaptability or versatility
If conventional catalysts are used, then manufacturing process is simplified, but the ability to produce copolymers with desirable properties is limited
Solution Approach 1:
The catalyst system incorporates specific local structural features including cyclopentadienyl and indenyl ligands on the metallocene compound, along with specific organoaluminum and organoboron compounds. These localized structural qualities enable the catalyst to produce copolymers with specific desired properties such as controlled density, flexibility, and mechanical characteristics that conventional catalysts cannot achieve.
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
These catalyst compositions achieve higher comonomer incorporation rates, enabling the production of low-density polyolefins with tailored properties, such as increased flexibility and reduced density, suitable for various applications, including elastomers.
Implementation Method 1
catalyst compositions and methods for the polymerization of olefin monomer to polyolefin... a catalyst composition comprising a tightly-bridged ansa-metallocene compound
Data Source
AI summary
The present techniques relate to catalyst compositions, methods, and polymers encompassing a Group 4 metallocene compound comprising bridged η5-cyclopentadienyl-type ligands, typically in combination with a cocatalyst, and an activator. The bridged η5-cyclopentadienyl-type ligands are connected by a cyclic substituent.