Cyclic Ammonium Salt Catalyst for Isocyanate Oligomerization
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Solution Overview
Problem
Existing isocyanate modification processes using tetraorganylammonium and phosphonium fluorides face issues with rapid catalyst decomposition and atypical reaction courses, leading to products with lower iminooxadiazinedione content and stability concerns, especially at higher temperatures.
Innovation Solution
A process utilizing cyclic ammonium salts with specific cation structures, such as those derived from N-substituted pyrrolidinium or piperidinium salts, as catalysts for isocyanate oligomerization, which are more stable and selective, allowing for higher iminooxadiazinedione group content and improved reaction control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tetraorganylammonium or phosphonium fluorides are used as catalysts for isocyanate modification, then the reaction proceeds quickly with high catalytic activity, but the catalyst decomposes rapidly at higher temperatures leading to atypical reaction courses and reduced product stability
Solution Approach 1:
The patent changes the chemical structure parameters of the catalyst by replacing tetraorganylammonium or phosphonium cations with cyclic ammonium cations having 5-7 membered rings. This structural modification maintains the catalytic activity while significantly improving thermal stability, allowing the catalyst to function reliably at higher temperatures without rapid decomposition
Solution Approach 2:
The patent creates a composite catalyst system by combining cyclic ammonium cations with specific anions (fluoride, hydrogen polyfluoride, or non-aqueous hydroxide). This composite structure leverages the stability of the cyclic ammonium framework while maintaining the high catalytic activity of the anionic component, achieving both productivity and reliability
2Productivity
If tetraorganylammonium (hydrogen) polyfluorides are used as catalysts, then high catalytic activity is achieved, but the reaction course becomes atypical with significantly lower iminooxadiazinedione group content
Solution Approach 1:
The patent modifies the cationic parameter from linear tetraorganylammonium or phosphonium structures to cyclic ammonium structures with 5-7 membered rings. This geometric and electronic parameter change alters the catalyst's interaction with the isocyanate, directing the reaction toward a typical course that produces the desired iminooxadiazinedione groups with controlled composition
3Manufacturing precision
If phosphonium salts are used as catalysts to eliminate atypical reaction courses, then product composition improves, but decomposition tendency increases unacceptably at higher reaction temperatures
Solution Approach 1:
The patent changes the cation type from phosphonium to cyclic ammonium. The cyclic ammonium structure provides superior thermal stability compared to phosphonium salts while maintaining the ability to control the reaction course. The ring structure resists decomposition at higher temperatures, eliminating the reliability issue while preserving manufacturing precision
4Ease of manufacture
If commercially readily available or easily produced catalysts are used, then ease of manufacture improves, but catalytic activity and selectivity may be insufficient or stability is compromised
Solution Approach 1:
The patent identifies cyclic ammonium salts as a class of compounds that can be easily synthesized from commercially available cyclic amines and alkyl halides. This parameter change in cation structure enables both ease of manufacture and superior catalytic performance with high stability, resolving the contradiction between accessibility and effectiveness
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 process achieves high-quality polyisocyanates with optimal iminooxadiazinedione content and improved stability, reducing anomalies in heat production and maintaining a uniform reaction course, resulting in versatile products for polyurethane production with enhanced properties.
Implementation Method 1
Ionic compounds have proven to be useful as modification catalysts because they can be used in very small amounts relative to the monomer to be converted and lead to the desired result extremely quickly
Data Source
AI summary
The invention relates to a process for modifying isocyanates where at least one organic isocyanate with NCO functionality > 1 is oligomerized in the presence of at least one catalyst, characterized in that the catalyst comprises, as isocyanate-modification catalysts, at least one cyclic ammonium salt having a cation of the formula (I) (formula I), where the N-containing substituents R1 and R2 are mutually independently identical or different aliphatic, cycloaliphatic, aromatic or araliphatic C1 to C20 moieties which are saturated or unsaturated, linear or branched, optionally substituted und/or interrupted by heteroatoms from the group of oxygen, sulphur and nitrogen, and Y is a substituted or unsubstituted, linear or branched C2 to C20 segment optionally interrupted by heteroatoms from the group of oxygen, sulphur and nitrogen or else interrupted by aromatic rings, and optionally containing other rings. The invention further relates to the use of such a catalyst.