Quinone Methide Stabilizer for Monomer Polymerization
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Solution Overview
Problem
Olefinically unsaturated monomers undergo unwanted polymerization during production and storage, leading to reactor deposits, reduced productivity, and safety concerns, with existing polymerization inhibitors and retarders having toxicity and environmental issues.
Innovation Solution
A stabilizer composition using quinone methides with specific electron-withdrawing groups as retarders, combined with nitroxyl radicals, which exhibit synergistic effects and reduced toxicity, effectively slowing down polymerization without the harmful effects of nitroaromatics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymerization inhibitors are used to completely prevent polymerization, then polymerization is effectively prevented, but they are used up quickly and require constant supply
Solution Approach 1:
The patent combines polymerization inhibitors (stable free nitroxyl radicals) with polymerization retarders (quinone methides with electron-withdrawing groups) into a single stabilizer composition. The inhibitor provides immediate strong protection while the retarder provides long-term protection, creating a multi-stage defense system that resolves the contradiction between immediate effectiveness and duration of action.
2Reliability
If nitroaromatics are used as polymerization retarders, then good retarding properties are achieved, but they are highly toxic and release environmentally harmful NOx gases
Solution Approach 1:
The patent changes the chemical structure parameter of the retarder from nitroaromatics to quinone methides with electron-withdrawing groups (such as cyano, carboxyl, ester, or amide groups). This structural parameter change maintains the retarding effectiveness while eliminating the toxic nitro group that releases harmful NOx gases, thus resolving the contradiction between effectiveness and environmental safety.
3Productivity
If olefinically unsaturated monomers are processed at elevated temperatures, then production efficiency is improved, but unwanted polymerization increases
Solution Approach 1:
The patent creates a composite stabilizer composition containing both polymerization inhibitors (stable free nitroxyl radicals with specific substitution patterns) and polymerization retarders (quinone methides with electron-withdrawing groups). This composite approach provides synergistic protection where the inhibitor handles immediate high-temperature polymerization risks during production, while the retarder provides extended protection, resolving the contradiction between production efficiency and polymerization stability.
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 composition significantly reduces polymerization in olefinically unsaturated monomers, maintaining low polymer content, minimizing reactor deposits, and reducing NOx emissions, while being easier to handle and more environmentally friendly.
Implementation Method 1
Polymerization retarders, on the other hand, can never completely prevent polymerization, but can only slow it down
Implementation Method 2
Polymerization inhibitors are, as the name suggests, able to completely prevent undesirable polymerizations
Implementation Method 3
Deposits of the polymer can, among other things, lead to reduced heat transfer in individual system components
Implementation Method 4
these olefinically unsaturated monomers are subjected to several purification process steps, such as distillation or Extraction to remove unwanted byproducts or contaminants
Data Source
Figure 1
AI summary
The invention relates to a process for stabilizing olefinically unsaturated monomers, characterized in that a retarder-containing composition, comprising a solvent and a quinone methide (II) as a retarder, is added to an olefinic unsaturated monomer or monomer mixture comprising at least one olefinically unsaturated monomer, and the resulting monomer composition. The monomers are defined as follows: X = halogen, -O-R3 or -S-R3, R1, R2 and R3 = hydrogen, alkyl, cycloalkyl or aryl group, each comprising 1 to 15 carbon atoms, wherein the substituents of the type R1, R2 and R3 are the same or different and are substituted or unsubstituted.