Bridged Metallocene Catalyst for Ethylene Interpolymer Production Rate
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Solution Overview
Problem
Current solution polymerization processes for producing ethylene interpolymers face challenges in achieving higher production rates, increasing molecular weight at higher reactor temperatures, and efficiently incorporating α-olefins to reduce density and optimize reactor feed ratios.
Innovation Solution
The use of a bridged metallocene catalyst formulation in a continuous solution polymerization process, involving multiple reactors operating at varying temperatures, allows for the production of ethylene interpolymers with improved properties. This formulation includes specific components such as a bulky ligand-metal complex, an alumoxane co-catalyst, a boron ionic activator, and a hindered phenol, optimized in specific molar ratios to enhance catalyst activity and polymer properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If reactor temperature is decreased to increase molecular weight, then polymer molecular weight increases, but solution viscosity becomes too high
Solution Approach 1:
The patent employs a bridged metallocene catalyst formulation that fundamentally changes the kinetic parameters of polymerization, enabling high molecular weight production at elevated temperatures where conventional catalysts would produce low molecular weight polymer due to excessive chain transfer reactions. The catalyst's unique structure maintains high activity and selectivity across a broader temperature range.
2Productivity
If conventional catalyst formulations are used, then production rate is limited, but increasing production rate reduces profitability
Solution Approach 1:
The bridged metallocene catalyst formulation dramatically increases polymerization rate constants, enabling production rates exceeding 10,000 pounds per hour while maintaining high catalyst efficiency and reducing operating costs through lower catalyst loadings and improved process intensity.
3Quantity of substance
If conventional catalysts are used, then α-olefin incorporation efficiency is low, but increasing α-olefin feed ratio increases process complexity
Solution Approach 1:
The bridged metallocene catalyst exhibits enhanced comonomer incorporation kinetics, achieving superior α-olefin incorporation efficiency at lower feed ratios. The catalyst's steric and electronic properties favor α-olefin insertion into the growing polymer chain, reducing the need for complex feedstock blending while maintaining desired polymer density and morphology.
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
This approach results in ethylene interpolymer products with increased molecular weight, improved density control, and enhanced production rates, while also reducing the amount of α-olefin required in the reactor feed, thus optimizing process efficiency and product properties.
Implementation Method 1
employing at least one bridged metallocene catalyst formulation to form an ethylene interpolymer product
Data Source
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AI summary
This disclosure relates to an improved continuous solution polymerization process wherein production rate is increased. Process solvent, ethylene, optional comonomers, optional hydrogen and a bridged metallocene catalyst formulation are injected into a first reactor to form a first ethylene interpolymer. Optionally, process solvent, ethylene, optional comonomers, optional hydrogen and a bridged metallocene catalyst formulation are injected into a second reactor forming a second ethylene interpolymer. The first and second reactors may be configured in series or parallel modes of operation. Optionally, a third ethylene interpolymer is formed in a third reactor, wherein a homogeneous catalyst formulation or a heterogeneous catalyst formulation is employed. In solution, the first, optional second and optional third ethylene interpolymers are combined, the catalyst is deactivated, the solution is optionally passivated and following a phase separation process an ethylene interpolymer product is recovered.