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A kind of method for preparing polyethylene terephthalate by terephthalic acid and ethylene glycol

A technology of polyethylene terephthalate and terephthalic acid, which is applied in the field of preparing polyethylene terephthalate, can solve the problems of waste, inability to synthesize polyester through polycondensation reaction, and inability to realize secondary utilization, etc. To avoid waste, avoid environmental pollution, and improve the effect of secondary utilization

Active Publication Date: 2018-12-18
JIANGSU JUJIE MICROFIBERS TEXTILE GRP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, most dyeing factories can process the residues of terephthalic acid produced by acid analysis of alkali reduction waste water and meet the discharge standards, but they cannot re-condense and utilize the obtained terephthalic acid, which has caused great harm. waste
Some dyeing factories are also carrying out the experimental development of secondary utilization. The re-extracted terephthalic acid is subjected to atmospheric pressure esterification to obtain bishydroxyethyl terephthalate (BHET). The terephthalic acid bulk density is only 0.3 ~ 0.4g / cm 3 , which is about 1 / 3 of the normal PTA, conventional test methods cannot synthesize polyester through polycondensation reaction, and cannot realize the value of its secondary utilization

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Terephthalic acid extracted from sea-island fiber residues, with a bulk density of 0.3g / cm 3 , according to the molar ratio of feed: terephthalic acid: ethylene glycol = 1: 1.2, first add ethylene glycol into the reactor and start to slowly heat up, when the temperature rises above 100°C, add terephthalic acid, and turn on the stirring at the same time The reactor was stirred, and the temperature of the reactor was gradually raised to 250°C to carry out the esterification reaction. The feeding was carried out in 3 times, and the same molar ratio was used for each feeding.

[0023] Add a fractionation column at the top of the reaction kettle, the temperature at the top of the fractionation column is controlled below 100°C, and the generated water is removed from the reaction system by distillation;

[0024] The intermediate bishydroxyethyl terephthalate undergoes polycondensation reaction in the presence of a catalyst system to obtain polyethylene terephthalate. The temp...

Embodiment 2

[0027] Terephthalic acid extracted from sea-island fiber residues, with a bulk density of 0.4g / cm 3 , according to the molar ratio of feed: terephthalic acid: ethylene glycol = 1: 1.5, first add ethylene glycol into the reactor and start to slowly heat up, when the temperature rises above 100°C, add terephthalic acid, and turn on the stirring at the same time The reactor was stirred, and the temperature of the reactor was gradually raised to 260°C to carry out the esterification reaction. The feeding was carried out in 4 times, and the same molar ratio was used for each feeding.

[0028] Add a fractionation column at the top of the reaction kettle, the temperature at the top of the fractionation column is controlled below 100°C, and the generated water is removed from the reaction system by distillation;

[0029] The intermediate bishydroxyethyl terephthalate undergoes polycondensation reaction in the presence of a catalyst system to obtain polyethylene terephthalate. The temp...

Embodiment 3

[0032] Terephthalic acid extracted from sea-island fiber residues, with a bulk density of 0.34g / cm 3 According to the molar ratio of feed, terephthalic acid: ethylene glycol = 1: 1.3, first add ethylene glycol into the reaction kettle and start to heat up slowly, when the temperature rises above 100°C, add terephthalic acid, and turn on the stirring at the same time The reactor was stirred, and the temperature of the reactor was gradually raised to 260°C to carry out the esterification reaction. The feeding was carried out in 4 times, and the same molar ratio was used for each feeding.

[0033] Add a fractionation column at the top of the reaction kettle, the temperature at the top of the fractionation column is controlled below 100°C, and the generated water is removed from the reaction system by distillation;

[0034] The intermediate bishydroxyethyl terephthalate undergoes polycondensation reaction in the presence of a catalyst system to obtain polyethylene terephthalate. T...

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Abstract

The invention discloses a method for preparing polyethylene terephthalate from terephthalic acid and glycol extracted from sea-island fiber residues. The method comprises the following steps of: (1) adding glycol into a reaction kettle, slowly raising the temperature, and after the temperature is raised to 100 DEG C or above, adding terephthalic acid, and stirring, so as to generate a midbody bis(2-hydroxyethyl)terephthalate, wherein the molar ratio of terephthalic acid to glycol is 1: (1.2-1.5),; (2) adding a fractionation column at the top of the reaction kettle and removing the generated water from the reaction system through distillation; and (3) carrying out polycondensation on the midbody bis(2-hydroxyethyl)terephthalate to obtain polyethylene terephthalate, wherein the reaction temperature is 250-285 DEG C, the pressure is lower than 50Pa and the time is 30-40 min. According to the method disclosed by the invention, polyethylene terephthalate is prepared through completing polycondensation by utilizing recovered PTA, so that the product utilization rate is improved.

Description

technical field [0001] The invention relates to a method for preparing polyethylene terephthalate from terephthalic acid and ethylene glycol. Background technique [0002] Terephthalic acid, also known as p-phthalic acid, is the most productive dicarboxylic acid, mainly produced from p-xylene, and is the main raw material for polyester production. It is solid at room temperature. It does not melt when heated, and sublimates above 300°C. If heated in an airtight container, it can melt at 425°C. Insoluble in water at room temperature. Mainly used in the manufacture of synthetic polyester resins, synthetic fibers and plasticizers. [0003] At present, most dyeing factories are able to process the residues of terephthalic acid produced by acid analysis of alkali reduction wastewater to meet the discharge standards, but they cannot re-condense and utilize the obtained terephthalic acid, which has caused great harm. waste. Some dyeing factories are also carrying out the expe...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G63/183C08G63/78
CPCC08G63/183C08G63/78
Inventor 仲鸿天沈松王平赵禹王伟峰丁良钰
Owner JIANGSU JUJIE MICROFIBERS TEXTILE GRP
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