Ethylene Polymer Melt Strength via Asymmetrical Polyene Segmentation
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Solution Overview
Problem
There is a need for ethylene-based polymers with higher melt strengths at both high and low densities that can be produced in a tubular reactor with low gel levels and reduced n-hexane extractable content.
Innovation Solution
The development of an ethylene-based polymer composition that includes an asymmetrical polyene incorporated into the polymerization process in a tubular reactor, with specific molecular weight and melt index relationships, and controlled polyene distribution to enhance melt strength and reduce gel formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multifunctional components are used to broaden molecular weight distribution and modify rheological properties, then melt strength is improved, but gel formation and fouling in the first reaction zone increase
Solution Approach 1:
The patent divides the polymerization process into multiple reaction zones (first reaction zone and second reaction zone) along the tubular reactor. By segmenting the reaction process and controlling the introduction of asymmetrical polyenes at specific zones, the patent achieves melt strength improvement while preventing gel formation and fouling in the first reaction zone.
Solution Approach 2:
The patent introduces asymmetrical polyenes at controlled locations (specifically at the second reaction zone or downstream) before the final polymerization stages. This preliminary action ensures that the polyenes are incorporated into polymer chains at appropriate conversion levels, achieving desired rheological properties without causing premature gelation or fouling.
2Strength
If asymmetrical polyenes are incorporated into the polymerization process, then melt strength is improved, but gel content increases
Solution Approach 1:
The patent applies local quality by introducing asymmetrical polyenes at specific locations (second reaction zone or downstream) rather than uniformly throughout the reactor. This localized introduction ensures that polyene incorporation occurs at appropriate conversion levels and polymer chain lengths, achieving melt strength improvement while minimizing gel content.
Solution Approach 2:
The patent changes the parameter of polyene introduction location and timing within the polymerization process. By controlling where and when asymmetrical polyenes are introduced (at the second reaction zone or downstream rather than the first), the patent optimizes the balance between melt strength enhancement and gel content control.
3Stability of the object's composition
If multifunctional components react at high conversion levels, then branching reactions occur, but intermolecular H-branch formation between large molecules leads to gel networks
Solution Approach 1:
The patent performs preliminary action by introducing asymmetrical polyenes at the second reaction zone or downstream, before the polymerization reaches very high conversion levels. This timing ensures that branching reactions occur at appropriate stages, forming desired polymer structures without leading to intermolecular crosslinking and gel network formation.
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 resulting polymer exhibits improved melt strength, density control, and reduced n-hexane extractables, suitable for applications such as extrusion coatings with minimal gel content.
Implementation Method 1
the reaction takes place in the presence of at least one free-radical initiator
Data Source
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AI summary
A composition comprising an ethylene-based polymer, the ethylene-based polymer having the following properties: a) at least one incorporated structure derived from a polyene selected from the group consisting of i) through x), as described herein; and b) a Mw(abs) versus I2 relationship: Mw(abs) < A + B(I2), wherein A = 2.40 x 105 g/mole and B = -8.00 x 103 (g/mole)/(dg/min). A composition comprising an ethylene-based polymer, the ethylene-based polymer comprising at least one incorporated structure derived from a polyene selected from the group consisting of i) through x), as described herein, wherein the polymer is formed in a reactor configuration comprising at least one tubular reactor.