Gas-Solid Diamine Acid Salt Formation for Polyamide Production
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Solution Overview
Problem
Existing processes for producing polyamides from diamine and dicarboxylic acid salts often require dissolution or dispersion in reaction media, leading to inefficiencies and challenges in salt recovery, and lack an optimized method for preparing semi-crystalline semi-aromatic polyamides.
Innovation Solution
A process involving contacting diamine gas with dicarboxylic acid at a temperature below the melting points of both, resulting in a solid/gas reaction that forms discrete salt particles without the need for reaction media, allowing for high conversion and efficient salt distribution, and subsequent solid-state polymerization to produce semi-crystalline polyamides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If diamine and dicarboxylic acid are contacted in solution or suspension, then the reaction can proceed, but the salt requires isolation and recovery from reaction media, increasing process complexity
Solution Approach 1:
The patent extracts the salt formation step from the solution/suspension process by using diamine gas phase reaction with solid dicarboxylic acid. This removes the need for salt isolation from reaction media, simplifying the process while maintaining manufacturing feasibility through direct gas-solid reaction.
Solution Approach 2:
The patent uses diamine gas as an intermediary medium to transfer reactants to the solid dicarboxylic acid particles. The gas phase acts as a mediator that enables reaction without requiring liquid or suspension media, eliminating the need for subsequent salt recovery operations.
2Productivity
If diamine is provided as gas, then the reaction is fast and leads to high conversion, but the reaction mixture must remain in solid state below melting points
Solution Approach 1:
The patent changes the physical state parameter of diamine from liquid/solution to gas phase, which dramatically increases reaction speed and conversion. To maintain solid state reaction mixture, the temperature is controlled below the melting points of both reactants and product, creating a unique gas-solid reaction system.
Solution Approach 2:
The patent exploits phase transition of diamine (liquid to gas) to enhance reaction kinetics. The diamine gas reacts with solid dicarboxylic acid particles, and the gas phase is subsequently removed, leaving high-conversion salt product. This phase change enables fast reaction while maintaining solid state reaction mixture.
3Manufacturing precision
If diamine gas is contacted with dicarboxylic acid particles, then effective distribution is achieved, but particle wetting and sticking risk increases
Solution Approach 1:
The patent uses gas phase diamine to contact solid acid particles, leveraging pneumatic principles to achieve effective distribution. The gas flow provides uniform contact with particles while the subsequent gas removal prevents liquid-like wetting and sticking, maintaining particle discreteness.
4Loss of energy
If no reaction media are used, then solvent handling is eliminated, but the reaction must proceed in solid state below melting points
Solution Approach 1:
The patent extracts the reaction media (solvent) from the process by using gas-phase diamine reaction with solid acid. This eliminates solvent handling and associated energy costs for heating, cooling, and recovery, while the reaction proceeds in solid state below melting points.
Solution Approach 2:
The patent uses phase transition of diamine (liquid to gas) to enable reaction without solvent. The gas phase allows rapid mixing and reaction, then condenses or is removed, leaving high-conversion salt. This phase change enables solvent-free reaction while maintaining energy efficiency.
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 method enables fast reaction with high conversion rates, reduces the risk of particle sticking and wetting, and eliminates the need for solvent handling, resulting in efficient production of semi-crystalline polyamides with improved yield and reduced energy costs.
Implementation Method 1
contacting a diamine gas, having a gas temperature T-gas, with a dicarboxylic acid, thereby forming a reaction mixture comprising diamine/ dicarboxylic acid salt
Implementation Method 2
The diamine is suitably provided as a gas; however the reaction mixture remains in the solid state
Data Source
AI summary
The invention relates to a process for preparing a salt from diamine and dicarboxylic acid, the process comprising contacting a diamine gas, having a gas temperature T-gas, with a dicarboxylic acid, thereby forming a reaction mixture comprising diamine/ dicarboxylic acid salt, wherein the dicarboxylic acid and the reaction mixture are kept at a temperature T-mixture of at least 10°C below the lowest of the melting temperature of the dicarboxylic acid (Tm-acid) and the melting temperature of the resulting diamine/ dicarboxylic acid salt (Tm-salt). The invention also relates to a process for preparing a polyamide comprising preparing a salt from diamine and dicarboxylic acid.