Method of adopting interface-solid phase polycondensation to prepare aromatic polyamide

Abstract

The invention discloses a preparation method of aromatic polyamide. The preparation method comprises following steps: (1) interface polycondensation: adding aromatic diacyl chloride, aromatic diamine,an organic solvent, and a water solution containing an acid binding agent into a reactor, mixing, carrying out reactions under strong stirring at a rotation speed of 200 to 1000 rpm, after reactions,washing the reaction product by water, separating, and drying to obtain a pre-polymer with a low molecular weight; and (2) solid phase polycondensation: under the protection of inert gas or in vacuum, making the low molecular weight pre-polymer carry out reactions to obtain aromatic polyamide. The interface polycondensation-solid phase polycondensation is adopted, through the solid phase polycondensation, the molecular weight (logarithmic viscosity number) of polyamide is increased; the shortages of a conventional interface polycondensation method are overcome; and the pre-polymer obtained through interface polycondensation and the final product prepared by solid phase polycondensation are both pure solid particles or powder. The prepared aromatic polyamide does not contain any impurity,and has a wide application range. The properties will not be influenced by the impurities during the polycondensation process of low temperature solutions. The inconvenience of transportation is overcome.

Description

technical field [0001] The invention belongs to the field of organic material synthesis, in particular to a method for preparing aromatic polyamide by interface-solid phase polycondensation. Background technique [0002] The special chemical structure of aromatic polyamide and its copolymer endows it with unique high and low temperature resistance, high modulus and high strength, electrical insulation, chemical stability and other properties, so it occupies a pivotal position in high-performance polymer materials. At present, the most commonly used method in the industry to prepare aromatic polyamides and their copolymers is to prepare aromatic polyamides and aromatic diamines through low-temperature solution polycondensation as raw materials. [0003] The use of low-temperature solution polycondensation method will inevitably produce side reactions, and the neutralization of the by-product hydrochloric acid will produce a large amount of inorganic salts, impurities and solv...

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Problems solved by technology

[0003] Using the low-temperature solution polycondensation method, side reactions will inevitably occur, and the neutralization of the by-product hydrochloric acid will produce a large amount of inorganic salts, impurities and solvents that are difficult to remove, thus affecting post-processing and product performance

DuPont of the United States proposed polyamide interfacial polycondensation (US3006899) ​​in the 1960s to obtain high-purity polyamide resins. On this basis, Teijin Corporation of Japan carried out process improvement and perfection (US3640970), and based on this In the past, aromatic polyamide molding powder (US4725392) was prepared by adding reinforcing materials (carbon fiber, aramid fiber, etc.). There are very few reports on interfacial polycondensation, only Ao Yuhui of Changchun University of Technology used a method similar to Teijin to report (Research on the preparation of isophthalamide m-phenylenediamine by interfacial polycondensation, Polymer Materials Science and Engineering, December 2012 Expect)

In 2017, Hu Zuming of Donghua University and others applied for a method for preparing high-purity polyamide particles by atomizing m-phenylene isophthalamide solution (a atomization preparation of m-phenylene isophthalamide solution particles) method, CN201711169454.1), but this method has complicated process, high requirements on equipment and high cost

[0004] The interface polycondensation method can overcome the shortcomings of low-temperature solution polymerization and obtain polyamide resins with high purity. However, the conventional one-step interfacial polycondensation method cannot obtain high molecular weight aromatic polyamides and their copolymers in batches due to mass transfer and heat transfer. Sensitive to many process conditions such as stirring, which is not conducive to stable industrial production

So far, the relevant reports on the interfacial polycondensation reaction of aromatic polyamide resins are all laboratory experiments, and there are no reports on the batch production method and equipment of interfacial polycondensation

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