Semi-aromatic polyamide production method and semi-aromatic polyamide

Abstract

The invention provides a semi-aromatic polyamide production method and semi-aromatic polyamide. The semi-aromatic polyamide production method includes the steps that firstly, diamine and binary acid are primarily charged in the amino-acid molar ratio smaller than 1.0, diamine, binary acid, water and a catalyst form slurry, and the slurry is heated and dissolved to form a salt solution; secondly, after it is detected that the salt solution is formed, the salt solution is dehydrated, the content of diamine in steam condensed water from a dehydration device is detected, the amino-acid molar ratio is adjusted to be larger than 1.0 by melting diamine and a molecular weight regulator, namely monoacid, and a pre-polymerization reaction is conducted; thirdly, a pre-polymerization reaction solution is subjected to vacuum flashing and then a post-polycondensation reaction is conducted. The content of gel in a semi-aromatic polyamide product is low, properties are excellent, and the application range is wide.

Description

technical field [0001] The invention relates to a production method of semi-aromatic polyamide and semi-aromatic polyamide, in particular to a continuous production method of low-gel semi-aromatic polyamide. Background technique [0002] Semi-aromatic polyamide is usually a polyamide with benzene ring structure obtained by polycondensation reaction of aromatic dibasic acid, aliphatic diacid and aliphatic diamine. Due to the introduction of the aromatic ring structure in the main chain, semi-aromatic polyamide has good heat resistance and mechanical properties, low water absorption, and has a more suitable cost performance, filling the general engineering plastic nylon and high temperature engineering The gap between plastic PEEK can be used in electronics, electrical appliances, automobiles, clothing fibers and other fields. [0003] The preparation of semi-aromatic polyamides usually adopts a prepolymerization-finishing reaction process. The prepolymerization reaction usu...

AI Technical Summary

Problems solved by technology

[0009] (1) Because the fusing point of aromatic dibasic acid exceeds its decomposition temperature, therefore, in the technique of existing literature report, the salt-forming reaction is all carried out in batches, and the ratio of dibasic acid and diamine in each batch of salt solution is different It is necessary to take samples for analysis and measurement, and then adjust according to the measurement results, which makes the prepolymerization reaction impossible to achieve true continuity

[0010] (2) The existing on-line test method can only quantitatively analyze the content of carboxyl-terminated and amino-terminated groups, but cannot analyze the composition of raw materials. Therefore, automatic control of the feeding process cannot be realized

[0011] (3) The amine and acid lost in the dehydration process cannot be continuously quantified, so it cannot be automatically adjusted according to the actual amine-acid ratio of the dehydrated material to stabilize the prepolymerization reaction

[0012] (4) The lag time for adjustment according to the end group content of the prepolymerization or polycondensation reaction outlet is long, and the amino acid ratio is prone to fluctuations during the adjustment process

However, if the amino acid ratio is too high, it is easy to cause side reactions of gelation, thereby reducing the quality of the product

Images