Olefin Polymerization Devolatilization Antioxidant Mediator
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Solution Overview
Problem
The existing devolatilization processes for polyolefins suffer from thermal degradation and oxygen infiltration, leading to altered physical properties of the final polymer pellets, such as melt index, polydispersity index, and molecular weight distribution, which deviate from the targeted properties.
Innovation Solution
The process involves adding antioxidant compounds to the polymeric solution before or during the devolatilization step, specifically in the first devolatilization chamber, to neutralize the detrimental effects of oxygen and maintain the integrity of the polymer chains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperatures are used in the devolatilization step to remove unreacted monomers, then the separation efficiency is improved, but thermal degradation of the polymer occurs
Solution Approach 1:
An antioxidant compound is introduced as an intermediary substance that mediates between the high temperature devolatilization process and the polymer chains. The antioxidant preferentially reacts with oxygen and prevents oxidative degradation, allowing the high temperature process to proceed without compromising polymer integrity.
Solution Approach 2:
The patent converts the harmful effect of oxygen present in the devolatilization atmosphere into a beneficial process by using the antioxidant to react with oxygen. This transforms what would be a degradation pathway into a protective mechanism that preserves polymer chains during the necessary high temperature separation process.
2Ease of operation
If oxygen is present in the devolatilization chamber, then the process is simpler to operate, but oxygen-induced chain breakage occurs
Solution Approach 1:
The antioxidant compound serves as a mediator that intercepts oxygen molecules before they can attack and break polymer chains. This intermediary substance allows oxygen to be present in the system without causing harmful oxidative degradation, maintaining both process simplicity and polymer integrity.
Solution Approach 2:
The antioxidant performs preliminary anti-action by preemptively reacting with oxygen molecules in the devolatilization chamber. This preliminary protection prevents oxygen from subsequently attacking and breaking polymer chains, thereby maintaining chain integrity while allowing the process to remain operationally simple.
3Productivity
If the polymeric solution is heated to high temperatures for devolatilization, then monomer removal is enhanced, but melt index and molecular weight distribution change
Solution Approach 1:
The antioxidant acts as a protective intermediary that shields polymer chains from thermal and oxidative stress during high temperature devolatilization. This allows aggressive monomer removal conditions to be applied without the expected degradation effects, thereby maintaining melt index consistency and molecular weight distribution.
Solution Approach 2:
The antioxidant provides beforehand cushioning by establishing protective chemical pathways before thermal degradation can occur. This preliminary protection cushions the polymer chains against the harsh thermal environment, allowing high productivity monomer removal while preserving manufacturing precision parameters.
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 effectively prevents thermal degradation and oxygen-induced chain breakage, ensuring that the physical properties of the polyolefin remain substantially unaltered, resulting in polymer pellets with consistent melt index, polydispersity index, and molecular weight distribution.
Implementation Method 1
adding antioxidant compounds to the polymeric solution before or during the devolatilization step, specifically in the first devolatilization chamber, to neutralize the detrimental effects of oxygen and maintain the integrity of the polymer chains
Implementation Method 2
the obtained polymeric solution is subjected to devolatilization in order to remove the unreacted monomers from the polyolefin
Implementation Method 3
a first devolatilization chamber operated at a temperature of 170-220° C. and a pressure from 2 to 12 bar. The polybutene-1 melt settles by gravity to the bottom of the chamber, while the evaporated monomers are realized away from the polymer, flowing upward as a gaseous stream
Data Source
AI summary
A process for the polymerization of one or more olefins under solution polymerization conditions to produce a polymeric solution, said process comprising contacting the produced polymeric solution with one or more antioxidant compounds before or concurrently with subjecting the polymeric solution to a devolatilization step to separate the polymer from the unreacted monomers.