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Method for preparing dioctyl terephthalate (DOTP) from waste and old polyethylene glycol terephthalate (PET) through near-critical alcoholysis

A technology of ethylene glycol phthalate and dioctyl terephthalate, applied in the field of waste polymer recycling, can solve the problems of long reaction time, high price, pollution, etc., and achieve fast reaction speed and high yield high effect

Inactive Publication Date: 2014-04-02
SHANGHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The alkaline hydrolysis method is to prepare terephthalic acid (TPA) by alkali hydrolysis and acidification of waste PET, and then react with isooctyl alcohol to obtain DOTP. This method has many intermediate processes, high cost and low yield, and its practical application is limited.
The alcoholysis method is to directly react waste PET with isooctyl alcohol, and obtain DOTP through alcoholysis and transesterification. This process is relatively simple, but in order to obtain a higher yield of DOTP, a suitable catalyst must be added, such as zinc acetate, titanic acid Tetrabutyl esters, etc., although the alcoholysis method has a great improvement over the alkaline hydrolysis method, there are disadvantages such as easy hydrolysis of the catalyst, high price, pollution, and long reaction time, and the product is not easy to purify, which limits the application.

Method used

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  • Method for preparing dioctyl terephthalate (DOTP) from waste and old polyethylene glycol terephthalate (PET) through near-critical alcoholysis

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] The waste PET was rinsed with deionized water, and dried in an oven at 45-65°C for 6 hours. The dried waste PET is put into a shredder and crushed into particles with a side length of about 2-4 mm. Accurately weigh 3 g of waste PET particles, put 12 g of isooctyl alcohol into a 40 ml high-temperature and high-pressure reactor and seal it. The reaction temperature is set at 300° C. and the reaction time is 3 h. After the reaction, quickly take out the reaction kettle and put it in an ice-water bath to cool. After cooling down to room temperature, the reaction solution is suction-filtered, deionized water is added to the filtrate, stirred and allowed to stand for stratification, and the lower clear liquid is rotary evaporated to remove water to obtain ethylene glycol. The supernatant was distilled under reduced pressure to remove isooctyl alcohol to obtain dioctyl terephthalate product. The degradation rate of waste PET polyester was 99%. A small amount of samples were ...

Embodiment 2

[0019] The waste PET was rinsed with deionized water, and dried in an oven at 45-65°C for 6 hours. The dried waste PET is put into a shredder and crushed into particles with a side length of about 2-4 mm. Accurately weigh 3 g of waste PET particles, put 12 g of isooctyl alcohol into a 40 ml high-temperature and high-pressure reactor and seal it. The reaction temperature is set at 300° C., and the reaction time is 3.5 h. After the reaction, quickly take out the reaction kettle and put it in an ice-water bath to cool. After cooling down to room temperature, the reaction solution is suction-filtered, deionized water is added to the filtrate, stirred and allowed to stand for stratification, and the lower clear liquid is rotary evaporated to remove water to obtain ethylene glycol. The supernatant was distilled under reduced pressure to remove isooctyl alcohol to obtain dioctyl terephthalate product. The degradation rate of waste PET polyester was 100%. A small amount of samples w...

Embodiment 3

[0021] The waste PET was rinsed with deionized water, and dried in an oven at 45-65°C for 6 hours. The dried waste PET is put into a shredder and crushed into particles with a side length of about 2-4mm. Accurately weigh 3 g of waste PET particles, put 12 g of isooctyl alcohol into a 40 ml high-temperature and high-pressure reactor and seal it. The reaction temperature is set at 300° C. and the reaction time is 4 h. After the reaction, quickly take out the reaction kettle and put it in an ice-water bath to cool. After cooling down to room temperature, the reaction solution is suction-filtered, deionized water is added to the filtrate, stirred and allowed to stand for stratification, and the lower clear liquid is rotary evaporated to remove water to obtain ethylene glycol. The supernatant was distilled under reduced pressure to remove isooctyl alcohol to obtain dioctyl terephthalate product. The degradation rate of waste PET polyester was 100%. A small amount of samples were ...

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Abstract

The invention relates to a method for preparing plasticizer dioctyl terephthalate (DOTP) from polyethylene glycol terephthalate (PET) waste plastics through alcoholysis and belongs to the technical field of waste polymer recovery and reutilization. According to the method adopting the near-critical isooctanol alcoholysis, the waste PET is fast depolymerized under the condition that catalysts are not added through the ester exchange reaction between the PET and the isooctanol, and the plasticizer DOTP is obtained. When the mass ratio of the PET to the isooctanol is 1:(3.5-4.5), the temperature is 300 to 350 DEG C, and the time is 3 to 4 hours, the degradation rate of the PET can reach 100 percent, and the recovery rate of the DOTP reaches higher than 80 percent. The method has the characteristics that the reaction speed is high, the yield is high, the environment is protected, and the like. The method belongs to a method for regenerating and reutilizing waste PET resources through chemical modification.

Description

technical field [0001] The invention relates to a method for preparing plasticizer dioctyl terephthalate (DOTP) by alcoholysis of polyethylene terephthalate (PET) waste plastics, and belongs to the technical field of waste polymer recycling. Background technique [0002] PET is widely used in the fields of beverage bottles, fibers, films, film substrates and electrical insulation materials due to its excellent performance. With the continuous increase of PET consumption, there is a problem of how to deal with polyester waste, such as Failure to recycle reasonably will not only cause a huge waste of resources, but also bring huge pollution to the environment. [0003] At present, the main treatment method of waste PET is direct recycling. However, due to the influence of impurities, thermal degradation and other reasons, the physical properties of recycled materials are low, and there are problems in transparency and sanitation, and their use is limited. In addition, the com...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C69/82C07C67/03C07C31/20C07C29/128
Inventor 陈晋阳刘锋徐天娇阮如意
Owner SHANGHAI UNIV