Ziegler-Natta Catalyst Blend for Propylene Polymer Processability
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Solution Overview
Problem
Propylene polymers produced with Ziegler-Natta catalysts using diether or succinate internal electron donors face limitations in processability due to narrow or broad molecular weight distribution, respectively, leading to mechanical and production-related issues.
Innovation Solution
A process involving a blend of Ziegler-Natta catalysts with titanium-halogen bonds supported on magnesium halide, using both diether and succinate compounds as internal electron donors, along with an organoaluminium compound and optional external donors, to achieve a balanced weight ratio for polymerization, resulting in propylene polymers with improved properties and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a Ziegler-Natta catalyst with a diether compound as internal electron donor is used, then narrow molecular weight distribution and very high isotacticity are achieved, but processability is limited
Solution Approach 1:
The patent combines two different Ziegler-Natta catalysts (one with diether internal donor and one with succinate internal donor) into a single catalyst blend. This merging allows the system to simultaneously achieve the high isotacticity from the diether catalyst and the improved processability from the succinate catalyst, resolving the contradiction between manufacturing precision and ease of operation
Solution Approach 2:
The invention creates a composite catalyst system by blending catalysts with different internal donors (diether and succinate) in specific weight ratios. This composite approach allows the final polymer to inherit beneficial properties from both catalyst types: high isotacticity from the diether component and broader molecular weight distribution from the succinate component, thereby improving processability
2Quantity of substance
If a Ziegler-Natta catalyst with a succinate compound as internal electron donor is used, then broad molecular weight distribution is achieved, but processability problems occur due to the broad distribution
Solution Approach 1:
The patent optimizes the weight ratio parameters of the catalyst blend (diether catalyst to succinate catalyst from 0.01 to 100, preferably 0.02 to 10, most preferably 0.1 to 1.5) to achieve the desired balance between molecular weight distribution breadth and processability. By adjusting these parameters, the system can control the extent of broadening while maintaining acceptable processability
3Ease of operation
If a blend of diether and succinate Ziegler-Natta catalysts is used, then balanced molecular weight distribution and improved processability are achieved, but more effort in production is required
Solution Approach 1:
The patent prepares the catalyst blend in advance before the polymerization process. By pre-mixing the diether and succinate catalysts in the specified weight ratios, the system simplifies the production process while still achieving the desired processability improvements, reducing the operational complexity during actual polymerization
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 yields propylene polymers with broad molecular weight distribution and high isotacticity, enhancing melt flow and processability, allowing for better extrusion and injection molding applications without requiring multiple reactors.
Implementation Method 1
polymerizing propylene and optionally one or more comonomers in presence of a blend of at least two Ziegler-Natta catalysts
Implementation Method 2
Ziegler-Natta catalysts with different internal donors... a Ziegler-Natta catalyst comprising a titanium compound having at least one titanium-halogen bond
Data Source
AI summary
The present invention relates to a process for the production of propylene polymers in the presence of a blend of a first Ziegler-Natta catalyst, which comprises a titanium compound having at least one titanium-halogen bond and a diether compound as internal electron donor, and a second Ziegler-Natta catalyst, which comprises a titanium compound having at least one titanium-halogen bond and a succinate compound as internal electron donor.