Method for preparing high-purity PET chip by using decoloration recovery of waste and old PET material

Abstract

The invention discloses a method for preparing a high-purity PET (polyethylene glycol terephthalate) chip by using decoloration recovery of a waste and old PET material. After the waste and old PET material is treated by a kneading machine, treated PET material is dissolved in a propylene glycol solution, filtration is performed, cooling crystallization is performed, squeezing is performed twice, dissolving is performed, crystallization is performed, and therefore a BHET [bis-(hydroxyethylterephthalate)] refined cake is obtained; then dissolving is performed by utilizing deionized water, crystallization is performed, distillation is performed, and therefore high-purity BHET powder is obtained; and condensation polymerization is performed, and therefore the high-purity PET chip is obtained. According to the invention, a bottleneck in a conventional process that just bottle chips which are cleaned thoroughly and dried and clean waste silk in a fiber plant can be recycled is solved, and therefore complexity required by equipment is greatly reduced, required solvent quantity is reduced, energy consumption is reduced, a recovery yield and product purity are improved, costs are reduced, secondary pollution does not exist, high recycling of the waste and old plastic is realized, and industrialization production can be performed.

Description

technical field [0001] The invention relates to waste PET recycling technology, in particular to a method for preparing high-purity PET slices through decolorization and recycling of waste PET materials. Background technique [0002] At present, the main methods of recycling waste PET materials in my country are chemical degradation and physical methods. The chemical method is to degrade the PET material under the action of heat and chemical reagents to form low-molecular products, which can be further utilized, such as monomers can be repolymerized, and oil products can be further processed, but this method requires high temperature and high pressure, which requires a lot of equipment. High conditions, high energy consumption, and harsh conditions make it difficult to achieve large-scale operations; the physical method is a recycling technology for reprocessing waste PET through cutting, crushing, heating and melting, but the performance of recycled PET is much higher than ...

AI Technical Summary

Problems solved by technology

The chemical method is to degrade the PET material under the action of heat and chemical reagents to form low-molecular products, which can be further utilized, such as monomers can be repolymerized, and oil products can be further processed, but this method requires high temperature and high pressure, which requires a lot of equipment. High conditions, high energy consumption, and harsh conditions make it difficult to achieve large-scale operations; the physical method is a recycling technology for reprocessing waste PET through cutting, crushing, heating and melting, but the performance of recycled PET is much higher than that of new materials. Reduced, and contains a lot of impurities, the application value is greatly reduced

Printed PET film can not be processed and recycled due to easy foaming, broken particles, blackened color and odor in the physical treatment, which is still a blank area in technology