Phthalate-Free Procatalyst Composition for Polypropylene
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Solution Overview
Problem
Current Ziegler-Natta catalyst systems for producing polyolefin polymers, particularly polypropylene, face limitations in catalyst activity, stereoselectivity, and molecular weight distribution, leading to suboptimal polymer properties and increased waste of internal electron donors.
Innovation Solution
A catalyst system utilizing a mixture of non-phthalate internal electron donors, specifically a combination of a magnesium moiety, a titanium moiety, and a mixed internal electron donor comprising a first and second internal electron donor, which enhances catalytic activity, stereoselectivity, and hydrogen response, resulting in improved molecular weight distribution and reduced waste of the first internal electron donor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single internal electron donor (e.g., phthalate) is used in Ziegler-Natta catalyst systems, then the catalyst provides adequate polymerization activity and stereoselectivity, but the catalyst activity is limited and molecular weight distribution is suboptimal
Solution Approach 1:
The patent combines two different internal electron donors (first internal electron donor and second internal electron donor) in a single catalyst system. This merging of two donor functions allows the catalyst to achieve both high activity and optimal molecular weight distribution, resolving the contradiction between productivity and manufacturing precision that existed when using a single donor.
Solution Approach 2:
The catalyst system uses a composite approach by incorporating multiple internal electron donors with different properties. The first and second internal electron donors work synergistically to provide both high catalytic activity and controlled molecular weight distribution, creating a composite catalytic system that overcomes the limitations of single-donor systems.
2Productivity
If conventional Ziegler-Natta catalyst systems are used, then polymerization can proceed, but catalytic residues are high and activity is relatively low
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by introducing a specific combination of internal electron donors. This parameter change results in higher catalytic activity and reduced catalytic residues in the polymer product, directly addressing the contradiction between productivity and substance loss.
3Adaptability or versatility
If phthalate-based internal electron donors are used, then good polymerization performance is achieved, but the catalyst system lacks optimal hydrogen response and molecular weight distribution for diverse end use products
Solution Approach 1:
The catalyst system achieves universality by using a combination of internal electron donors that provides both optimal molecular weight distribution and improved hydrogen response. This multi-functional capability allows the catalyst to produce polymers suitable for diverse end use products while maintaining reliable performance across different application requirements.
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 catalyst system achieves increased catalytic activity, improved stereoselectivity, and optimal molecular weight distribution, reducing xylene solubles and increasing the melt flow rate of polypropylene, while minimizing the consumption and waste of internal electron donors.
Implementation Method 1
a catalyst system for producing polyolefin polymers that utilizes a mixture of two non-phthalate internal electron donors
Data Source
AI summary
A phthalate-free procatalyst composition is disclosed for olefin polymerization that exhibits excellent polymerization activity and response to hydrogen, and can produce a polyolefin exhibiting high stereoregularity, high melt flow rate, and desirable molecular weight distribution. The method for producing the procatalyst composition includes reaction of a magnesium support precursor with a tetravalent titanium halide and a combination of different internal electron donors. The first internal electron donor may comprise one or more substituted phenylene aromatic diester and the second internal electron donor may comprise a polyether, preferably a 1,3-diether. In one embodiment, the support precursor comprises a spherical spray crystalized MgCl2-EtOH adduct.