Heterogeneous Ziegler-Natta Catalyst for Polyethylene Density Control
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Solution Overview
Problem
Conventional Ziegler-Natta catalysts produce ethylene-based polymers with high amounts of high density fractions, which limits their optical and film mechanical properties, and there is a need for catalysts with high efficiency that can reduce these fractions.
Innovation Solution
Development of heterogeneous procatalysts containing a titanium species, a non-reducing transition metal compound, a chlorinating agent, and a magnesium chloride component, which are combined in a specific process to reduce the high density fraction of ethylene-based polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional Ziegler-Natta catalysts are used for ethylene polymerization, then catalyst activity is maintained, but high density fractions in the polymer increase, deteriorating optical and film mechanical properties
Solution Approach 1:
The patent modifies the catalyst composition by incorporating specific electron donors (cyclic esters, cyclic carbonates, cyclic carbamates) and adjusting the Ti/Mg ratio to optimize polymer density distribution. These parameter changes in catalyst composition enable better control over high density fraction without excessive complexity
Solution Approach 2:
The patent creates a composite catalyst system combining TiCl4, MgCl2 support, and specific electron donors in defined ratios. This composite approach integrates multiple functional components that work synergistically to control polymer density while maintaining manageable catalyst complexity
2Manufacturing precision
If catalyst composition is simplified to reduce high density fraction, then polymer properties improve, but catalyst efficiency decreases
Solution Approach 1:
The patent optimizes the concentration ranges of electron donors (0.1-10 equivalents relative to Ti) and Ti/Mg ratios (0.1-10) to simultaneously achieve high density fraction reduction and maintain catalyst efficiency. These precise parameter adjustments balance polymer quality with productive output
Solution Approach 2:
The patent introduces specific electron donors with particular molecular structures (cyclic esters, carbonates, carbamates) that locally modify the catalyst active sites. These localized modifications at specific catalyst sites enable selective control over polymer density without compromising overall catalyst activity and efficiency
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 described process significantly reduces the high density fraction in polyethylene copolymers, improving their properties and increasing catalyst efficiency.
Implementation Method 1
heterogeneous procatalysts may contain a titanium species, a non-reducing transition metal compound having a structure M(OR1)z
Implementation Method 2
a chlorinating agent having a structure A(Cl)x(R2)3-x
Data Source
AI summary
The heterogeneous procatalyst of this disclosure includes a titanium species; a hydrocarbon soluble transition metal compound having a structure M(OR1)z; a chlorinating agent having a structure A(Cl)x(R2)3-x, and a magnesium chloride component. M of M(OR1)z is a non-reducing transition metal other than titanium, the non-reducing transition metal being in an oxidation state of +2 or +3. Each R1 is independently (C1-C30)hydrocarbyl or —C(O)R11, where R11 is (C1-C30)hydrocarbyl. Subscript z of M(OR1)z is 2 or 3. Each R1 and R11 may be optionally substituted with one or more than one halogen atoms, or one or more than one —Si(RS)3, where each RS is (C1-C30)hydrocarbyl. A of A(Cl)x(R2)3-x is aluminum or boron; R2 is (C1-C30)hydrocarbyl; and x is 1, 2, or 3; and a magnesium chloride component.