Ethylene Polymerization Reactor Zoning for Melt Strength and Fouling Control
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Solution Overview
Problem
There is a need for processes that can be used in combination with coupling and/or branching components with differentiated monomeric reactivity to form ethylene-based polymers with improved melt strength, especially for film and extrusion coating applications, while minimizing preheater fouling and gel formation.
Innovation Solution
A process involving polymerization of ethylene and an asymmetrical polyene with an alpha, beta unsaturated carbonyl end and a C-C double bond end in the presence of a free-radical initiator, conducted in a reactor configuration with at least two reaction zones, where the second zone is downstream from the first, to optimize the incorporation and reactivity of the polyene and prevent fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multifunctional components with high reactivity are used to increase melt strength, then polymer rheology is improved, but preheater fouling and gel formation increase
Solution Approach 1:
The patent introduces a pre-reaction zone before the main reaction zone where the multifunctional component is pre-mixed with the initiator at lower temperature and pressure conditions. This preliminary action allows controlled initiation of the multifunctional component, reducing its reactivity before entering the preheater, thereby minimizing fouling and gel formation while still achieving the desired melt strength enhancement in the final polymer.
Solution Approach 2:
The patent creates different reaction conditions in different zones along the reactor. The pre-reaction zone has lower temperature and pressure with controlled initiator concentration, while the main reaction zone has higher temperature and pressure for complete polymerization. This local differentiation allows the multifunctional component to react controllably without causing excessive fouling in the preheater while still achieving the desired melt strength.
2Productivity
If the multifunctional component is added at the beginning of the reaction zone, then incorporation efficiency is high, but fouling and gel formation occur
Solution Approach 1:
The patent divides the reaction process into multiple segments: a pre-reaction zone for initial incorporation and a main reaction zone for complete polymerization. By segmenting the reaction zones and controlling the timing of multifunctional component addition, the patent achieves high incorporation efficiency while preventing fouling and gel formation that would occur if all reactions happened simultaneously at high temperature.
Solution Approach 2:
The pre-reaction zone serves as a preliminary stage where the multifunctional component is partially reacted under controlled conditions before the main polymerization. This preliminary action ensures high incorporation efficiency while controlling the reactivity to prevent fouling and gel formation in subsequent high-temperature zones.
3Productivity
If high conversion levels are achieved in a single reaction zone, then productivity is high, but control over molecular architecture becomes difficult
Solution Approach 1:
The patent segments the polymerization process into a pre-reaction zone and a main reaction zone. The pre-reaction zone handles the initial incorporation of multifunctional components at lower conversion, while the main reaction zone completes the polymerization. This segmentation maintains high overall conversion while allowing precise control over molecular architecture through zoned reaction conditions.
Solution Approach 2:
The patent employs dynamic control of reaction conditions along the reactor length, adjusting temperature, pressure, and initiator concentration in different zones. This dynamic approach allows the system to achieve high conversion while maintaining control over molecular architecture by adapting reaction conditions to the specific stage of 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
This process enhances the melt strength of ethylene-based polymers and reduces the risk of fouling and gel formation, achieving improved polymer properties for film and extrusion coating applications.
Implementation Method 1
polymerizing ethylene and at least one asymmetrical polyene... wherein the polymerization takes place in the presence of at least one free-radical initiator
Data Source
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AI summary
A process to form an ethylene-based polymer including polymerizing ethylene and at least one asymmetrical polyene comprising an "alpha, beta unsaturated - carbonyl end" ("α,β unsaturated - carbonyl end") and a "C-C double bond end," wherein the polymerization takes place in the presence of at least one free-radical initiator; and wherein the polymerization takes place in a reactor configuration comprising at least two reaction zones, reaction zone 1 and reaction zone i (i ≥ 2), wherein reaction zone i is downstream from reaction zone 1.