Synthesis method of long-carbon-chain semi-aromatic nylon

Abstract

The invention relates to the field of synthesis of semi-aromatic nylon, in particular to a synthesis method of long-carbon-chain semi-aromatic nylon. The synthesis method comprises the following stepsof mixing a wet powdery nylon salt, an antioxidant, a catalyst, a surfactant and pellets, and carrying out one-step solid-phase polymerization in a dynamic mixing state to obtain powdery nylon, underdynamic mixing, enabling the small pellets to promote material stirring and mixing and reducing material adhesion to the wall, wherein the one-step solid-phase polymerization comprises solid-phase pre-polymerization and solid-phase post-polymerization, in the solid-phase pre-polymerization process, ensuring nylon salt and a pre-polymerization product not to be molten, in the solid-phase post-polymerization process, gradually reducing the system pressure to vacuum, and keeping the system pressure in a vacuum state for at least 1 hour, wherein the temperature of the solid-phase post-polymerization is not lower than the termination temperature of the solid-phase pre-polymerization. The synthesis method is a practical industrial large-scale production scheme, the product is non-sticky to thewall, the apparent shape of the product is white powdery nylon, the product can be directly used for molding processing without further granulation, and the overall quality of the product is very good.

Description

technical field [0001] The invention belongs to the field of synthesis of semi-aromatic nylon, in particular to a method for synthesizing long carbon chain semi-aromatic nylon. Background technique [0002] Long carbon chain semi-aromatic nylon (mainly PA10T, PA11T, PA12T, PA13T, PA14T) is a type of semi-aromatic nylon prepared by polycondensation of long carbon chain diamine and terephthalic acid. Compared with short carbon chain semi-aromatic nylon (PA4T, PA5T and PA6T), the melting point of long carbon chain semi-aromatic nylon is lower than 350°C (the temperature at which semi-aromatic nylon begins to decompose during processing is 350°C), which is It is determined that it can be used alone without introducing a third component for copolymerization, thus maintaining the regularity of the molecular chain; at the same time, the introduction of long carbon chains in the repeating unit makes it have good flexibility. Long carbon chain semi-aromatic nylon not only has good h...

AI Technical Summary

Problems solved by technology

CN 103360598 A, CN107383365 A, CN 109970968 B introduced the use of "one-step" melt polymerization in a polymerization kettle to prepare semi-aromatic nylon, but this preparation method has many disadvantages, such as high polymerization temperature, high energy consumption, and side reactions , the product is easy to form gel, yellow, the melt viscosity is high, it is difficult to discharge, and there are many residues on the wall of the kettle; if things go on like this, black spots will be generated, which seriously affects its appearance quality and performance

CN 104327265 A and CN 101768266 A introduce the use of "one-step" solid-phase polymerization in a polymerization kettle to prepare semi-aromatic nylon, but during the polymerization process, there will be lumpy products due to the melting of part of the raw materials, which will block the discharge pipe, resulting in failure to discharge normally. material, so it cannot be applied to industrial production

CN 105339415 A introduces the preparation of semi-aromatic nylon by "one-step" solid-state polymerization using a closed small cup (the small cup cover has a small opening for balancing the environmental pressure), but when the temperature is raised under normal pressure, the nylon salt will be decomposed into two Amines and dibasic acids, and part of the diamines will be discharged in the form of steam, resulting in an imbalance in the molar ratio of the two, unable to increase the molecular weight of the product

CN 104817693 A introduces the use of drum reactors for salt formation and polymerization to prepare PA11T, but nylon 11T salt is easily soluble in water, that is, the essence of this reaction is solution polymerization, and the product is easy to stick to the wall and cannot be discharged

CN 110467724 A has introduced the utilization drum reactor to prepare semi-aromatic nylon, and it has following problems: (1) the minimum melting point of nylon 66 prepolymer is only 145 ℃ (Pierfrancesco Cerruti, etal.Chemiluminescence from oxidation of polyamide 66.I. The oxidation of purepolyamide.), which makes the temperature of solid-phase polymerization of its nylon salt must be lower than 145°C, otherwise, solid-phase polymerization cannot be carried out smoothly, and in Examples 1-3, the initial reaction temperature is directly set to 180°C , Nylon 66 prepolymer will melt and stick to the wall, and powdery products cannot be obtained; (2) When the reaction is vented and vacuumed, there is no relevant design inside the equipment to prevent the powdery product from going out, which is easy to block the pipeline; (3) A baffle is installed on the stirring shaft inside the drum reactor, which will seriously affect the maintenance of the equipment and reduce the efficiency of the equipment

In short, there are many problems in the polymerization equipment and method described in this patent, and the expected purpose cannot be achieved

Images