Polyamide Batch Production Pressure Control
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Solution Overview
Problem
Current methods for producing polyamide by polycondensation of a diamine component and a dicarboxylic acid component face challenges such as foaming, solidification, heat degradation, low yield, and quality defects due to the use of solvents and inadequate control of mole balance, leading to inefficient and economically problematic batchwise production.
Innovation Solution
A batchwise production method involving a diamine component with 70 mol% or more of xylylenediamine, including 20 mol% or more of p-xylylenediamine, is used in a reaction tank with a partial condenser, where the inner pressure is controlled to maintain a fluid state and reduce pressure gradually, preventing adhesion and allowing precise mole balance control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the diamine component is added to the dicarboxylic acid component under atmospheric pressure, then the reaction can proceed without additional equipment, but the dicarboxylic acid component sublimates and deposits on the ceiling and pipes, causing clogging and quality defects
Solution Approach 1:
The patent changes the pressure parameter from atmospheric pressure to pressurized conditions (maintaining pressure higher than the vapor pressure of the dicarboxylic acid component). This parameter change prevents sublimation of the dicarboxylic acid component, eliminating deposition on pipes and ceiling, thus ensuring production continuity while using standard equipment
2Stability of the object's composition
If a large amount of solvent water is used in the polycondensation reaction, then the reaction can proceed homogeneously, but a large amount of energy is required to remove the water and the single batch yield is low
Solution Approach 1:
The patent changes the solvent system from aqueous to non-aqueous (using the dicarboxylic acid component itself as the solvent). This eliminates the need to remove large amounts of water, significantly reducing energy consumption while maintaining reaction homogeneity through the molten state of the dicarboxylic acid
3Ease of operation
If the inner pressure of the reaction tank is not controlled during diamine addition, then the operation is simpler, but the mole balance cannot be precisely controlled leading to quality variations
Solution Approach 1:
The patent implements pressure control as a feedback mechanism during diamine addition. By maintaining the inner pressure at a specific level (higher than the vapor pressure of the dicarboxylic acid), the system prevents diamine loss and ensures precise mole balance control, achieving both operational simplicity and manufacturing precision
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 results in high polyamide yield, uniform quality, reduced yellowing, and continuous batch production without clogging, using less equipment and energy, thus being economically advantageous.
Implementation Method 1
a batchwise reaction tank equipped with a partial condenser
Implementation Method 2
the aqueous solution of nylon salt is heated under pressure in a single reaction vessel to allow the polymerization to proceed in a homogeneous phase while preventing the diamine component from escaping by evaporation
Implementation Method 3
Since the molten dicarboxylic acid component is sublimable, the sublimated dicarboxylic acid component deposits on the ceiling of the polymerization apparatus
Data Source
AI summary
An economical batchwise production method of polyamide with good quality by the polycondensation in which a diamine component including 70 mol% or more of a xylylenediamine which includes 20 mol% or more of p-xylylenediamine is added to a dicarboxylic acid component in a batchwise reaction tank equipped with a partial condenser. The diamine component is added while maintaining the whole reaction system in fluid state under pressure. The pressure is reduced during the time that the molar ratio is within a specific range while continuing the addition.