Xylene Diisocyanate Composition With Low-Boiling Compound Control
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Solution Overview
Problem
Existing methods for preparing xylene diisocyanate result in high impurity content due to side reactions, affecting the quality and yield of polyurethane resins, and are either costly or inefficient for industrial production.
Innovation Solution
A method involving controlled reaction conditions, including a salt-forming reaction with specific solvents and phosgenation, to limit low-boiling-point compounds to 1% or less, ensuring high-purity xylene diisocyanate production with improved process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If phosgenation method is used to prepare xylene diisocyanate, then production cost is reduced, but impurity content increases due to side reactions
Solution Approach 1:
The patent applies preliminary action by pre-treating the amine compound through salt formation with hydrogen chloride before the phosgenation reaction. This preliminary salt-forming step modifies the amine's reactivity and prevents side reactions during the subsequent phosgenation, thereby reducing impurity content while maintaining cost-effectiveness. The salt form of the amine reacts more selectively with phosgene, avoiding unwanted side reactions that would occur with free amine compounds.
2Productivity
If reaction conditions are not controlled, then production speed is maintained, but content of low-boiling-point compounds increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the reaction temperature and time during the phosgenation process. By optimizing these parameters, the reaction proceeds at high speed while minimizing the formation of low-boiling-point compounds. The controlled temperature ensures selective formation of the desired xylene diisocyanate product rather than unwanted side products with lower boiling points.
3Manufacturing precision
If high-purity xylene diisocyanate is produced, then quality of polyurethane resin is improved, but yield decreases
Solution Approach 1:
The patent applies the extraction principle by selectively removing low-boiling-point compounds from the reaction mixture through distillation or fractional distillation. This separation process extracts the unwanted impurities while retaining the desired high-purity xylene diisocyanate product, thereby achieving both high purity and high yield. The low-boiling-point compounds are removed as a separate fraction, preventing them from contaminating the final product.
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 method achieves high-purity xylene diisocyanate with reduced impurities, enhancing product quality and yield while optimizing economic efficiency.
Implementation Method 1
reacting an amine compound with hydrogen chloride in a solvent at 20°C to 90°C under normal pressure to obtain an amine salt compound
Implementation Method 2
reacting the amine salt compound with phosgene to obtain a reaction mixture including a xylene isocyanate compound
Implementation Method 3
removing the solvent and unreacted phosgene from the reaction mixture to prepare the xylene diisocyanate composition
Data Source
AI summary
Provided is a technology regarding to a xylylene diisocyanate composition in which the content of low-boiling-point compounds is controlled, and a preparation method thereof. Provided is a technology regarding to a xylylene diisocyanate composition capable of preparing a high-purity xylylene diisocyanate compound in a high yield by controlling purity of an amine compound and controlling the content range of low-boiling-point compounds in a reactant upon preparing xylylene diisocyanate using phosgene, and a preparation method thereof.