Diisocyanate Trimerization via High-Boiling Solvent Extraction
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Solution Overview
Problem
The existing methods for producing isocyanurates from volatile and moderately volatile diisocyanates require costly and inconvenient distillative removal of excess monomeric diisocyanates, leading to thermal stress and residual non-light-stable aromatic components in the end product.
Innovation Solution
Using diisocyanates with a boiling point above 350°C as solvents to trimerize volatile and moderately volatile diisocyanates, with a trimerization catalyst, to achieve a composition where at least 60% of the volatile diisocyanates are converted to trimers or oligomers, thereby eliminating the need for distillative removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillative removal of excess monomeric diisocyanate is performed, then the proportion of residual monomers is reduced, but the process becomes costly and inconvenient with additional apparatus complexity and thermal stress
Solution Approach 1:
The harmful component (monomeric diisocyanate) is extracted from the reaction mixture by forming a percolate layer that selectively contains the monomer, allowing its removal without complex distillation apparatus
Solution Approach 2:
The solubility parameters are changed by selecting a percolate component whose solubility in the reaction mixture is between that of the monomeric diisocyanate and the trimer/oligomer, enabling selective separation based on solubility differences rather than requiring thermal distillation
2Manufacturing precision
If distillation is used to remove monomeric diisocyanate, then residual monomer content is reduced, but thermal stress alters the product causing discolouration
Solution Approach 1:
The mechanical/thermal distillation system is replaced with a solubility-based liquid-liquid extraction system using a percolate component, eliminating thermal stress that causes product discolouration while still achieving monomer removal
3Ease of manufacture
If aromatic isocyanates are used in mixed trimerization, then the process is simplified, but non-light-stable aromatic components remain in the end product
Solution Approach 1:
The percolate component is specifically selected to have solubility characteristics that enable it to preferentially dissolve aromatic monomeric isocyanates while leaving the trimer/oligomer phase unaffected, providing targeted removal of light-unstable components
4Productivity
If monoalcohol is used as cocatalyst in trimerization, then the reaction proceeds, but functionality and NCO content are reduced and inhibitors must be added
Solution Approach 1:
The percolate component extracts and removes the alcohol cocatalyst along with the monomeric isocyanate from the reaction mixture, restoring the full functionality and NCO content of the trimer/oligomer product without requiring inhibitor addition
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 process reduces the residual monomer content to less than 20% by weight, enhancing the stability and usability of the end product while avoiding thermal stress and the use of distillation, thus improving the industrial viability and safety by minimizing hazardous diisocyanate release.
Implementation Method 1
Using diisocyanates with a boiling point above 350°C as solvents to trimerize volatile and moderately volatile diisocyanates
Implementation Method 2
with a trimerization catalyst, to achieve a composition where at least 60% of the volatile diisocyanates are converted to trimers or oligomers
Data Source
AI summary
A process for preparing trimers and/or oligomers of diisocyanates is disclosed along with a composition of trimers and/or oligomers formed from diisocyanates and monomeric diisocyanates obtainable by reaction of I. 5-94.999% by weight of A) at least one diisocyanate having a boiling point of less than 250° C. (at standard pressure) and/orB) at least one diisocyanate having a boiling point of 250-350° C. (at standard pressure), in the presence of II. 94.999-5% by weight ofC) at least one diisocyanate having a boiling point above 350° C. (at standard pressure), III. in the presence of at least one trimerization catalyst in amounts of 0.001% to 5% by weight, and the amounts of I.-III. add up to 100% by weight.