Ethylene Polymerization CTA Ratio Optimization
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Solution Overview
Problem
Conventional processes for producing ethylene-based polymers with high melt strength and G′ values for film and extrusion coating applications face issues such as product gels and process instability, along with high consumption and costs due to the use of highly reactive multifunctional components.
Innovation Solution
A process involving a coupling and/or branching component combined with a low-activity Chain Transfer Agent (CTA) system, where a higher concentration of CTA is fed preferentially to downstream reaction zones in a reactor configuration with multiple zones, optimizing the CTA activity ratio to achieve desired product characteristics while reducing instability and fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If highly reactive multifunctional components are used to increase G′ and melt strength, then the desired high G′ value products are achieved, but product gel formation and process instability occur
Solution Approach 1:
The patent changes the concentration parameter of multifunctional components from high to low (0.001-0.5 wt% range), and compensates by optimizing other parameters such as CTA concentration and reactor temperature profile. This parameter transformation resolves the contradiction by achieving similar melt strength enhancement without the harmful effects of high concentrations
Solution Approach 2:
The patent introduces Chain Transfer Agents (CTA) as intermediary substances that mediate between the multifunctional components and the polymerization process. The CTA controls the reaction kinetics and branching density, allowing the multifunctional components to contribute to melt strength while preventing gel formation and process instability
2Strength
If highly reactive multifunctional components are used to achieve high G′ values, then the desired product performance is obtained, but consumption and costs increase
Solution Approach 1:
The patent transforms the concentration parameter from high to low (specifically 0.001-0.5 wt% range), demonstrating that low concentrations of multifunctional components are sufficient to achieve the desired G′ values when combined with optimized CTA systems and reactor conditions
Solution Approach 2:
The patent enables the polymerization system to self-regulate branching density and molecular weight distribution through the synergistic interaction between multifunctional components and CTA, eliminating the need for excessive amounts of expensive multifunctional additives
3Strength
If highly reactive multifunctional components are used to increase melt strength, then higher G′ performance is achieved, but fouling formation potential increases
Solution Approach 1:
The patent changes the concentration parameter of multifunctional components to low levels (0.001-0.5 wt%), which reduces their reactivity and tendency to form gels and foul reactor surfaces, while maintaining melt strength enhancement through optimized CTA interactions
Solution Approach 2:
The CTA acts as an intermediary that controls the reaction pathways, preventing direct polymerization of multifunctional components that would lead to fouling, while still allowing them to contribute to branching and melt strength
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 allows for the production of ethylene-based polymers with increased G′ values while minimizing product gel formation and process instability, leading to lower consumption and costs, and improving the properties of films and extrusion coatings.
Implementation Method 1
polymerizing a reaction mixture comprising ethylene, at least one symmetrical polyene and at least one chain transfer agent system comprising at least one CTA; wherein the polymerization takes place in the presence of at least one free-radical initiator
Implementation Method 2
at least one chain transfer agent system comprising at least one CTA; wherein the ratio of 'the activity of the CTA system of the feed to the first reaction zone' to 'the activity of the CTA system of the cumulative feed to the reaction zone i,' (Z1/Zi), is ≤(0.8−0.2*log(Cs))
Data Source
AI summary
A process to form an ethylene-based polymer comprises polymerizing a reaction mixture comprising ethylene, at least one symmetrical polyene and at least one chain transfer agent system comprising at least one chain transfer agent (CTA) in the presence of at least one free-radical initiator and 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. The ratio of “the activity of the CTA system of the feed to the first reaction zone” to the “activity of the CTA system of the cumulative feed to the reaction zone i,” (Z1/Zi), is less than or equal to (0.8−0.2*log(Cs)), wherein Cs is from 0.0001 to 10.