Continuous solid-phase condensation polymerization method for producing high-temperature-resistant nylon

Abstract

The invention belongs to the field of nylon preparation, and particularly relates to a continuous solid-phase condensation polymerization method for producing high-temperature-resistant nylon. The continuous solid-phase condensation polymerization method comprises the following steps: continuously feeding a starting material, and continuously discharging after passing a reactor combination to obtain a powdery nylon product, wherein the starting material comprises a wet powdery nylon salt, a catalyst and an antioxidant, the solvent content of the wet powdery nylon salt is 5-20%, and the starting material is subjected to continuous solid-phase polymerization in the reactor combination. By adopting the method, the polymerization period is greatly shortened, the polymerization efficiency is improved, the automation degree is also improved, and the labor intensity of workers is reduced; solid-phase condensation polymerization is adopted, so that the problem of wall adhesion is avoided, the reaction temperature is reduced, side reactions are reduced, and the obtained product is excellent in physical and mechanical properties and stable in quality; and different combinations of three sections of polymerization reactors are adopted, so that the process adjustment space is large, and the requirements of different molecular weights of different varieties of nylon or the same nylon can be met.

Description

technical field [0001] The invention belongs to the field of nylon preparation, in particular to a continuous solid-phase polycondensation method for producing high-temperature-resistant nylon. Background technique [0002] There are many types of high temperature resistant nylon prepared by polycondensation, mainly including PA46, PA9T, PA10T, PA12T, PA6T / 66, PA6T / 6I, PA12T / 6T, PA10C, PA12C, PA10N, PA12N, etc. This type of nylon not only has good heat resistance, high strength and low water absorption, but also has good toughness and good forming and processing properties, which makes it widely used in the automotive and electrical and electronic industries, and the market demand continues to increase. The field of application is gradually expanding. [0003] Most of the industry adopts intermittent "two-step" polycondensation to prepare high-temperature-resistant nylon: firstly, a prepolymer with lower viscosity and better fluidity is prepared by melt prepolymerization in...

AI Technical Summary

Problems solved by technology

However, there are many deficiencies in this polymerization method, such as: during the prepolymerization process, the prepolymer inevitably remains in the kettle, causing each batch of materials to be mixed with the previous batch of materials, which affects product quality; The reaction temperature is as high as 260°C and the reaction time ranges from ten hours to dozens of hours, resulting in high energy consumption and low efficiency in production, and the product is easy to form gel, yellow, or even black spots, which affects product performance and appearance

CN103539934A reports a method for continuous copolymerization to prepare semi-aromatic nylon: first use diamine, dibasic acid and chain extender to form a salt, then melt and pre-polymerize in an autoclave, and then granulate through an extruder. Finally, solid-phase post-polymerization is carried out in a drum reactor, but it is still semi-continuous polymerization in essence. The reaction temperature of solid-phase post-polymerization is as high as 280-300°C, and the time is 72-144h. Too high temperature and too long time Seriously affect production efficiency, and the product quality is poor

[0004] In order to solve the deficiency of "two-step" polycondensation to prepare high-temperature-resistant nylon, in recent years, there have been more and more reports on the preparation of nylon by solid phase batch polymerization: CN104327265A, CN101768266A, CN105339415A, CN104817693A, CN110467724A and other related patents introduce the preparation of high-temperature-resistant nylon by intermittent solid-state polycondensation: a certain amount of nylon salt is added to the drum reactor, and nylon is prepared through high pressure, normal pressure and vacuum; This method has a short reaction cycle, which solves the problem that the product in the traditional method ("melt prepolymerization + solid phase postpolymerization") is easy to form gel, yellow, or even produce black spots, and obtains white powdery nylon with excellent performance. , and high-viscosity products can be obtained without chain extenders, but in actual production, it has the disadvantages of low degree of automation, high dependence on labor, high labor intensity and low production efficiency

Images