A method for recycling caprolactam

Abstract

The invention relates to a method for recycling caprolactam. The method comprises the following steps: synthesizing polyamide 6 from caprolactam; obtaining an extracting solution from a polymerizationproduct by utilizing a vacuum extraction method; heating the extracting solution until the extracting solution is molten, performing vacuum filtration to remove floccules to obtain high-purity caprolactam which is caprolactam with the cyclic dimer content of 0.5-1wt%, mixing the high-purity caprolactam with other reaction raw materials, and performing a ring-opening reaction and a condensation polymerization reaction to obtain polyamide 6. According to the method disclosed by the invention, 8-10wt% of hot water extractable substances generated by thermodynamic equilibrium in a caprolactam hydrolytic polymerization process can be recycled; moreover, the extracting solution hardly contains water, and most of cyclic dimers are removed by filtering, so that the content of oligomers in generated polyamide 6 slices is low, the adverse effect of higher content of cyclic oligomers on the product quality and equipment is reduced, and the product quality is improved.

Description

technical field [0001] The invention belongs to the technical field of polymer material preparation, and relates to a method for recycling caprolactam. Background technique [0002] At present, my country's polyamide nylon 6 slice polymerization process mainly refers to foreign imported equipment and foreign advanced technology, which mainly include Gemma, Evanda-Car Fischer, Agafel, Noy and so on. The imported equipment and processes are all used from the caprolactam melter, titanium dioxide preparation device, benzoic acid configuration device, caprolactam feeding tower, pre-polymerization tower, post-polymerization tower, pelletizer, extraction tower, drying tower and Ancillary equipment for conveying packaging. The production process of polyamide 6 polymerization is that molten caprolactam is fed together with water and molecular weight regulator, and the product is obtained through pre-polymerization, post-polymerization, pelletizing, extraction and drying. [0003] I...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to overcome the defects of large energy resource consumption and limited content during reuse and compounding existing in the existing polyamide 6 polymerization technology, and to provide a method for recycling caprolactam, through multi-stage The extraction of the vacuum system enables the efficient recycling of the thermodynamic equilibrium products produced during the polymerization process, and reduces the moisture in the recycled materials, so that the recycled materials can be directly recycled, eliminating the traditional three-effect evaporation process and reducing The energy consumption required for processing in the recycling process

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