Investigation of the process of solid-phase dopolyamidation of polyamide-6 granulate
Now the development of alternative technological solutions for the production and preparation for conversion of polyamide-6 to obtain polymer granules with the required physicochemical parameters is highly relevant. To create a rational technological process for obtaining polyamide-6 granulate, ready for conversion it is very important to investigation for fundamentally new technical and technological solutions that allow obtaining low-molecular and high-molecular products at various thermodynamic parameters of polymer synthesis. There are two alternative ways of preparing polyamide-6 granulate for conversion: 1) The industry at concerns to produce fiber-forming polyamide-6, such as KuibyshevAzot (Togliatti), BASF (Germany), uses a method consisting of extraction of low-molecular compounds with subsequent drying and isolation of low-molecular compounds from polyamide-6 granules by evaporation. 2) A technological process developed at ISUCT, which consists in the sequential carrying out of the processes of dopolyamidation of the prepolymer of polyamide-6 and the combined drying-demonomerization of the obtained polyamide-6granulate. A process developed for solid-phase dopolyamidation of polyamide-6 granulate, which makes it possible to increase the degree of conversion of caprolactam into a polymer up to 96.5-97.5% and to synthesize a high-molecular-weight polymer with a predominantly linear structure of macromolecules, which makes it possible to obtain high quality products during its conversion: plastic products, composite materials, textile fibers, textile fiber for technical purposes, technical and cord fibers for the production of rubber products, tire cord for the production of tires for various purposes. To carry out the process of solid-phase dopolyamidation, a laboratory-scale pilot plant was created and put into operation. During investigation, the synthesis of a prepolymer - granulate ofpolyamide-6 by the method of solid-phase dopolyami-dation at various times of the process was carried out. The content of low-molecular compounds and the relative viscosity before and after the process of solid-phase dopolyamidation have been determined. To determine the properties of polyamide-6 granulate, the methods of extraction, sublimation and viscometry were used. Based on the analysis of experimental data, the optimal parameters of the solid phase dopolyamidation process have been determined, during which it is possible to obtain a granulate that fully meets modern requirements for a granulate ready for conversion into threads, fibers, and plastic products.