Half-Metallocene Catalyst Ligand Control for Polyolefin Processability

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Solution Overview

Problem

Conventional polyolefin production using Ziegler-Natta and chromium-based catalysts results in polymers with wide molecular weight distribution and nonuniform composition, making it difficult to impart desired properties, while metallocene catalysts offer narrow distribution but face challenges in processing due to high extrusion load and surface roughness.

Innovation Solution

A novel half-metallocene catalyst compound is developed, coordinating a cyclopentadienyl ligand with a Group 15 or 16 element-containing ligand, allowing for control of molecular weight and distribution, and enhancing thermal stability, thereby facilitating polyolefin production with improved processability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional Ziegler-Natta or chromium-based catalysts are used for polyolefin production, then the polymer has wide molecular weight distribution, but the composition distribution is nonuniform making it difficult to impart desired properties

Engineering Contradiction:

Improvemolecular weight distribution widthVSAvoidcomposition distribution uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent employs metallocene catalysts with specific ligand structures (cyclopentadienyl ligands with various substituents) to control the polymerization reaction parameters, achieving uniform comonomer incorporation while maintaining wide molecular weight distribution. The single-site nature of metallocene catalysts ensures consistent active sites, leading to uniform composition distribution.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If metallocene catalysts are used to achieve narrow molecular weight distribution and controlled properties, then ease of adjustment of molecular weight and stereoregularity is improved, but processing problems occur due to high extrusion load and surface roughness

Engineering Contradiction:

Improvecontrol of molecular weight and stereoregularityVSAvoidhigh extrusion load and surface roughness

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces specific substituent groups (such as bulky aryl groups, alkyl groups) at particular positions on the cyclopentadienyl ligands to modify local properties of the catalyst. This local modification affects the polymer chain structure and distribution, enabling control over extrusion characteristics and surface properties while maintaining the benefits of metallocene catalysts.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates composite catalyst systems by combining metallocene compounds with specific ligands (amido groups, cyclopentadienyl groups with various substituents) and activators. This composite approach allows tuning of both molecular weight distribution and processing properties, resolving the contradiction between controlled polymer properties and processability.

Inventive Principle:

Principle #40Composite materials

3Reliability

If half-metallocene catalyst compounds with monocyclopentadienyl ligand and amido group are used, then thermal stability is superior and molecular weight is very high, but molecular weight distribution is very narrow causing processing problems

Engineering Contradiction:

Improvethermal stabilityVSAvoidmolecular weight distribution width

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent divides the ligand structure into distinct functional segments: a cyclopentadienyl group providing thermal stability and a separately attached amido group with specific substituents. This segmentation allows independent optimization of thermal stability (from cyclopentadienyl) and molecular weight distribution control (from amido group substituents), resolving the contradiction between high molecular weight and narrow distribution.

Inventive Principle:

Principle #1Segmentation

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 achieves high molecular weight and wide molecular weight distribution, ensuring superior processability and properties, with controlled molecular weight through substituent variation, and improved thermal stability, addressing the limitations of existing metallocene catalysts.

Implementation Method 1

a cyclopentadienyl ligand is coordination-bonded to a transition metal or a transition metal halogen compound

Methodology Applied

Scientific EffectCoordination bonding:

Implementation Method 2

method of producing an olefin polymer including bringing the above catalyst composition into contact with an olefin monomer

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentEP3708596B1Novel metallocene catalyst compound for production of polyolefin resin or method of preparing same

Publication Date: 2024.03.27 DL CHEM CO LTD

Figure 1

AI summary

The present invention relates to a novel metallocene catalyst compound for the production of a polyolefin resin having a high molecular weight and a wide molecular weight distribution or a method of preparing the same, and more particularly to a metallocene catalyst compound using a ligand containing a Group 15 or 16 element having a bulky substituent or a method of preparing the same. The present invention provides a novel metallocene catalyst compound represented by Chemical Formula 1 below. [Chemical Formula 1] (L1){(N-L2)Z1(Y)Z2(N-L3)}(X)M