Copolyamide Resin Production via Controlled Vapor Phase Temperature
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Solution Overview
Problem
The production of copolyamide resins with p-xylylenediamine and adipic acid faces challenges such as uneven mechanical and heat resistance properties due to local formation of high melting point polyamides, adhesion issues in the polymerization process, and difficulties in achieving uniform quality, leading to inefficiencies and economic problems in batchwise production methods.
Innovation Solution
A copolyamide resin is produced with a diamine component comprising 70 mol% or more of xylylenediamine, including 20 mol% or more of p-xylylenediamine, and a dicarboxylic acid component comprising 70 mol% or more of straight-chain aliphatic dicarboxylic acids, using a batchwise reaction method with continuous or intermittent addition of the diamine to molten dicarboxylic acid under controlled pressure and temperature, preventing local formation of high melting point polyamides and ensuring uniform quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a copolyamide is produced using p-xylylenediamine and adipic acid by conventional batchwise method, then the production process can be completed, but local formation of high melting point polyamides occurs causing uneven mechanical properties and heat resistance
Solution Approach 1:
The patent applies preliminary action by heating the vapor phase in the reaction tank to a temperature equal to or higher than the melting point of the nylon salt before adding 80% of the total diamine component. This pre-heating ensures that when the diamine is added, the nylon salt remains in a molten state and distributes uniformly throughout the reaction system, preventing local formation of high melting point polyamides and ensuring homogeneous composition throughout the copolyamide product.
2Productivity
If batchwise polycondensation is conducted with large amount of water removal, then polymerization can proceed to completion, but polymer adheres to reaction vessel wall causing heat degradation and quality issues
Solution Approach 1:
The patent applies parameter changes by maintaining the vapor phase temperature at or above the nylon salt melting point throughout the polycondensation process. This temperature parameter control prevents the nylon salt from solidifying and adhering to the reaction vessel wall during water removal, thereby preventing heat degradation and ensuring uniform quality throughout the polyamide product while maintaining high batch yield.
3Productivity
If high pressure equipment is used for polycondensation, then reaction efficiency improves, but equipment complexity and cost increase
Solution Approach 1:
The patent applies self-service by utilizing the heat generated from the exothermic polycondensation reaction itself to maintain the vapor phase temperature at or above the nylon salt melting point. This self-heating mechanism eliminates the need for external high-pressure equipment or additional heating systems, achieving efficient polycondensation while simplifying equipment requirements and reducing costs.
4Productivity
If excessive heating is applied to remove water, then water removal efficiency improves, but polymer adheres to stirring shaft causing production interruptions
Solution Approach 1:
The patent applies parameter changes by precisely controlling the vapor phase temperature to be at or above the nylon salt melting point but not excessively high. This optimized temperature parameter allows efficient water removal through controlled evaporation while preventing polymer adhesion to the stirring shaft, enabling continuous production without interruptions.
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 results in copolyamide resins with excellent mechanical, heat resistance, and molding properties, allowing for continuous batchwise production without clogging or polymer accumulation, reducing the need for high-pressure equipment and excessive heating, and producing high-quality molded articles with stable properties.
Implementation Method 1
subjecting the diamine component and the dicarboxylic acid component to a polycondensation reaction in the absence of a solvent
Implementation Method 2
the water vapor in the system is gradually released to reduce the pressure finally to atmospheric pressure or reduced pressure
Implementation Method 3
keeping the reaction system at a temperature which allows a whole reaction system to be kept in fluid state
Data Source
AI summary
A copolyamide resin for molding including a diamine component which includes two or more diamines and a dicarboxylic acid component. The diamine component includes 70 mol % or more of a xylylenediamine which includes 20 mol % or more of p-xylylenediamine and the dicarboxylic acid component includes 70 mol % or more of a straight-chain aliphatic dicarboxylic acid having 6 to 18 carbon atoms. The copolyamide resin contains particles having a major diameter of 50 µm or more in an amount of 1000 particles/g or less, the particles being made of a polyamide having a melting point higher than that of the copolyamide resin by 20 °C or more when measured by a differential scanning calorimetry. The copolyamide resin has very uniform and stable properties and is excellent in any of mechanical properties, heat resistance, chemical and physical properties, and molding properties. An efficient production method of the copolyamide resin, its resin composition, and its molded article are also described.