Process for production of polyamide

摘要

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.

主权项

1. A method of producing polyamide, comprising:
(1) charging a dicarboxylic acid component into a batchwise reaction tank equipped with a partial condenser and increasing an inner pressure of the reaction tank to 0.2 MPaG or higher; (2) adding a diamine component to the dicarboxylic acid component continuously or intermittently until a molar ratio (B/A) of the diamine component (B) to the charged dicarboxylic acid component (A) reaches 0.60, while maintaining the inner pressure of the reaction tank at 0.2 MPaG or higher and maintaining a whole reaction system in a fluid state; (3) reducing the inner pressure of the reaction tank to 0.1 MPaG or lower and atmospheric pressure or higher during the time when the molar ratio (B/A) of the diamine component (B) to the charged dicarboxylic acid component (A) is within a range of from 0.60 to 0.95, while maintaining the whole reaction system in a fluid state and adding the diamine component to the dicarboxylic acid component continuously or intermittently; and (4) after completing the adding in (3), maintaining the inner pressure of the reaction tank at the time when the adding in (3) is completed for from 5 minutes to 3 hours, while maintaining the whole reaction system in the fluid state, wherein the diamine component comprises 70 mol % or more of a xylylenediamine, and the xylylenediamine comprises 20 mol % or more of p-xylylenediamine, and polycondensation of the diamine component and the dicarboxylic acid component is conducted in the absence of a solvent.