Dual Metallocene Catalyst for Broad Molecular Weight Polyolefins
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Solution Overview
Problem
Dual-site catalysts in polymerization reactions face challenges in controlling heterogenization and activation, leading to inconsistent performance and reactivity issues, particularly with metallocene catalysts, which often result in dominating structures and require specific conditions for effectiveness.
Innovation Solution
A catalyst composition comprising bridged metallocene compounds with indenyl, tetrahydroindenyl, cyclopentadienyl, and fluorenyl groups, along with optional activators and co-catalysts, is used to create a dual catalyst system that can operate in a single reactor, producing polyolefins with broad molecular weight distributions and improved co-monomer incorporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate catalyst injections are used, then flexibility is improved, but costs increase and polymer homogeneity becomes difficult to achieve
Solution Approach 1:
The patent combines multiple catalyst functions into a single dual-site catalyst particle, merging catalyst A and catalyst B into one integrated system. This eliminates the need for multiple separate catalyst injection systems, reducing equipment complexity and operational costs while maintaining the ability to produce bimodal resins with different molecular weight distributions in a single reactor.
2Device complexity
If dual-site catalyst is used in single reactor, then costs are reduced, but control of heterogenization and activation becomes difficult
Solution Approach 1:
The patent applies local quality by creating distinct active sites within the catalyst particle with different properties. Catalyst A and catalyst B are embedded in the support matrix at different locations or with different orientations, allowing each site to perform its specific function (one for high molecular weight, one for low molecular weight) while maintaining overall control of the heterogenization and activation processes.
3Productivity
If metallocene catalysts are used, then reactivity is improved, but heterogenization control becomes difficult leading to dominating structures
Solution Approach 1:
The patent uses a composite catalyst system consisting of metallocene compounds supported on a solid support material. The support acts as a matrix that stabilizes the metallocene active sites and prevents them from aggregating into dominating structures. The composite structure maintains the high reactivity of metallocene while providing uniform distribution and controlled heterogenization through the support matrix.
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 dual catalyst system enhances polymerization activity and mechanical properties, allowing for the production of ethylene-copolymers with broad molecular weight distributions and improved co-monomer incorporation, suitable for various applications such as film products and rotomoulding.
Implementation Method 1
catalyst composition comprising: catalyst component A comprising a bridged metallocene compound... catalyst component B comprising a bridged metallocene compound... polymerizing the monomer... in the presence of the at least one catalyst composition
Data Source
AI summary
The present invention relates to a catalyst composition comprising:catalyst component A comprising a bridged metallocene compound with two tetrahydroindenyl groups, each group being unsubstituted or substituted;catalyst component B comprising a bridged metallocene compound with a substituted or unsubstituted cyclopentadienyl group and a substituted or unsubstituted fluorenyl group;an optional activator; an optional support; and an optional co-catalyst.The present invention also relates to a polymerization process using said composition. The invention further relates to olefin polymers at least partially catalyzed by said catalyst composition and articles comprising said olefin polymers.