Aliphatic Isocyanate Preparation via Segmented Phosgenation
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Solution Overview
Problem
The preparation of high purity aliphatic isocyanate is hindered by side reactions and high energy consumption due to the need for high temperature and reactivity in phosgenation reactions, leading to impurities and increased production costs.
Innovation Solution
A method involving a two-step phosgenation reaction process where an aliphatic amine salt is formed at a lower temperature, followed by a second reaction with phosgene in the presence of an organic solvent, with unreacted materials being separated, condensed, and recycled, reducing energy consumption and side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature heating is applied to increase reaction yield, then the reaction efficiency is improved, but side reactions are generated and product purity deteriorates
Solution Approach 1:
The patent divides the single high-temperature phosgenation reaction into two separate reaction stages: first forming the amine salt at lower temperature (40-80°C), then reacting with phosgene at controlled temperature (60-100°C). This segmentation allows each stage to operate under optimal conditions, preventing side reactions while maintaining high yield.
Solution Approach 2:
The patent changes the temperature parameter throughout the process - initially maintaining lower temperature (40-80°C) during salt formation, then controlling the phosgenation temperature (60-100°C). This dynamic parameter adjustment prevents thermal denaturation and side reactions while ensuring complete reaction and high productivity.
2Productivity
If continuous high temperature heating is maintained to progress the reaction, then reaction rate is improved, but energy consumption increases
Solution Approach 1:
The patent performs preliminary action by forming the amine salt at lower temperature (40-80°C) before the phosgenation reaction. This preliminary step reduces the overall energy requirement because the subsequent phosgenation can proceed at moderate temperature (60-100°C) without requiring continuous high-temperature heating, thus maintaining reaction rate while reducing energy consumption.
3Productivity
If high temperature processing is used to ensure complete reaction, then conversion efficiency is improved, but thermal denaturation of products occurs
Solution Approach 1:
The patent segments the reaction process into two distinct stages with different temperature profiles: salt formation at 40-80°C and phosgenation at 60-100°C. This prevents thermal denaturation by avoiding excessive temperature exposure while ensuring complete conversion through the second controlled heating stage.
Solution Approach 2:
The patent maintains continuous useful action by implementing a two-stage continuous process where the amine salt formed in the first stage is immediately used in the second stage. This continuous flow ensures complete conversion efficiency while the controlled temperature progression prevents thermal denaturation throughout the process.
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 significantly reduces energy consumption and side reactions, allowing for the production of high purity aliphatic isocyanate with reduced production costs and minimized exposure to high temperatures, thereby improving yield and resin quality.
Implementation Method 1
sending a mixture comprising hydrogen chloride, unreacted phosgene and a solvent to a condenser to condense
Implementation Method 2
sending the separated unreacted phosgene and solvent to a distillation column to recover unreacted phosgene to the upper stage and separate the solvent to the lower stage
Data Source
Figure 1
AI summary
The present invention relates to a method for preparing aliphatic isocyanate. More specifically, the present invention relates to a high purity isocyanate preparation method that can effectively recover unreacted materials and recycle them to a reaction step, and reduce energy consumed when separating reactants.