阅读说明：本技术 一种低萃取膜用聚酯切片的合成方法 (Synthetic method of polyester chip for low-extraction film ) 是由 段旻 刘勤学 姚孝平 孔云飞 马强 杨彩怡 于 2021-08-05 设计创作，主要内容包括：本发明涉及一种低萃取膜用聚酯切片的合成方法,属于聚酯制备技术领域,包括以下步骤：1)酯化反应,2)预缩聚反应；3)终缩聚反应；4)将步骤3中得到的PET原片与磷酸酯、冠醚、双酚内烯氧化合物进行熔融捏合,熔融温度为280℃,熔融时间为5min；本发明中采用25％KF/Al-2O-3和纳米三氧化二锑作为复配的催化剂,可以减少三氧化二锑的添加量,降低了杂质的引入,相比于乙二醇锑,本发明中添加三氧化二锑,由于单价以及后续无需除水的原因,使用成本更低,且可以克服乙二醇锑极易吸湿,包装开封后必须1次全部用完的不足。预缩聚阶段,反应物料浓度较低,分子链小,所以本发明中在预缩聚阶段匀速提高真空度可以避免物料大量带出造成泛液。(The invention relates to a synthetic method of polyester chips for a low-extraction membrane, belonging to the technical field of polyester preparation and comprising the following steps: 1) esterification reactionAnd 2) pre-polycondensation reaction; 3) final polycondensation reaction; 4) carrying out melt kneading on the PET original sheet obtained in the step 3, phosphate, crown ether and bisphenol endoolefine oxygen compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min; in the invention, 25 percent of KF/Al is adopted 2 O 3 Compared with ethylene glycol antimony, the antimony trioxide added in the invention has lower use cost due to the reason of unit price and subsequent need of water removal, and can overcome the defects that the ethylene glycol antimony is very easy to absorb moisture and needs to be completely used up for 1 time after packaging and unsealing. In the pre-polycondensation stage, the concentration of reaction materials is low, and molecular chains are small, so that the constant speed improvement of the vacuum degree in the pre-polycondensation stage can avoid flooding caused by carrying out a large amount of materials.)

1. A synthetic method of polyester chip for low extraction film is characterized in that: the synthesis method comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 110-130 parts of ethaneGlycol and 0.1-0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the nitrogen atmosphere, and the temperature is 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.01 to 0.012 part of antioxidant 618, 10 to 20 parts of third monomer, 0.02 to 0.03 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

2. The method for synthesizing polyester chip for low extraction film according to claim 1, wherein: the 25% KF/Al₂O₃The mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.2-0.5: 1.

3. The method for synthesizing polyester chip for low extraction film according to claim 2, wherein: the 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.32: 1.

4. The method for synthesizing polyester chip for low extraction film according to claim 1, wherein: the third monomer is selected from naphthalene dicarboxylic acid.

5. The method for synthesizing polyester chip for low extraction film according to claim 1, wherein: the addition amount of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 0.002-0.05 percent of the mass of the PET original sheet.

6. The method for synthesizing polyester chip for low extraction film according to claim 5, wherein: the mass ratio of the phosphate to the crown ether to the bisphenol endoalkenyloxy compound is 2 (2-5) to 1.

7. The method for synthesizing polyester chip for low extraction film according to claim 6, wherein: the mass ratio of the phosphate to the crown ether to the bisphenol endoalkenyloxy compound is 2:3: 1.

Technical Field

The invention relates to a synthetic method of a polyester chip for a low-extraction membrane, belonging to the technical field of polyester preparation.

Background

PET (polyethylene terephthalate) is a milky white or pale yellow, highly crystalline polymer with a smooth and glossy surface. The high-temperature-resistant and high-frequency-resistant composite material has excellent physical and mechanical properties in a wider temperature range, the long-term use temperature can reach 120 ℃, the electrical insulation property is excellent, even under high temperature and high frequency, the electrical property is still good, but the corona resistance is poor, and the creep resistance, the fatigue resistance, the friction resistance and the dimensional stability are good.

PET materials are widely applied to the fields of engineering plastics, films, bottle flakes and fibers due to good performance of the PET materials, but the PET materials can generate side product oligomers in production at present. Have an impact on the subsequent fiber production process and product quality, for example: the pollution of the low molecular polymer to the film can influence the subsequent printing, aluminizing, coating and film temperature resistance, and the amorphous PET low molecular polymer has poor temperature resistance. Therefore, the breadth of the molecular weight distribution of film-grade PET chips is limited to a certain range, and even then, the production of low-molecular polymers in PET after processing cannot be avoided. Because the polycondensation temperature and the degradation temperature in the PET synthesis process are the same (both 280-290 ℃), the reaction carried out in the polycondensation reaction kettle is reversible all the time, when the low molecular weight continuously polymerizes the long-chain molecules with high molecular weight, the high molecular weight is also continuously degraded into short chains with low molecular weight, although certain measures are taken for processing equipment and processes, the generation of the short-chain molecules with low molecular weight is difficult to avoid, and the processing of PET necessarily has the existence of low molecular weight polymers.

Therefore, the research for reducing the content of oligomer in the polyester chip becomes the important point of the research in the industry.

Disclosure of Invention

The purpose of the invention is: the synthetic method of the polyester chip for the low-extraction film overcomes the defects in the prior art, is simple in process and low in cost, and can obviously reduce the content of low-extraction substances in the PET film.

In order to achieve the technical purpose, the technical scheme of one aspect of the invention is as follows:

a synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 110-1.6 kg/cm of ethylene glycol and 0.1-0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.01 to 0.012 part of antioxidant 618, 10 to 20 parts of third monomer, 0.02 to 0.03 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Further, the 25% KF/Al₂O₃The mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.2-0.5: 1.

Further, the 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.32: 1.

Further, the third monomer is selected from naphthalene dicarboxylic acid.

Furthermore, the addition amount of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 0.002-0.05 percent of the mass of the PET original sheet.

Furthermore, the mass ratio of the phosphate to the crown ether to the bisphenol internal alkenyloxy compound is 2 (2-5) to 1.

Further, the mass ratio of the phosphate to the crown ether to the bisphenol endoalkenyloxy compound is 2:3: 1.

Compared with the prior art, the invention has the beneficial effects that:

in the invention, 25 percent of KF/Al is adopted₂O₃Compared with ethylene glycol antimony, the antimony trioxide added in the invention has lower use cost due to the reason of unit price and subsequent need of water removal, and can overcome the defects that the ethylene glycol antimony is very easy to absorb moisture and needs to be completely used up for 1 time after packaging and unsealing. In the pre-polycondensation stage, the concentration of reaction materials is low, and molecular chains are small, so that the constant speed improvement of the vacuum degree in the pre-polycondensation stage can avoid flooding caused by carrying out a large amount of materials.

According to the invention, the PET original sheet obtained in the step 3 is melt-kneaded with phosphate, crown ether and bisphenol endoalkenyloxy compound, the melting temperature is 280 ℃, the melting time is 5min, the cyclic trimer can be inhibited by adopting the step process, and experiments prove that the content of the cyclic trimer generated by the synthesis process is 0.2% of the content of commercial PET under the same condition.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

The sources of the raw materials in the invention are:

terephthalic acid: industrial grade, certified chemical fiber limited;

ethylene glycol: industrial grade, chemical reagents ltd of the national drug group.

Cobalt acetate: shanghai Huating chemical plant, Inc.;

nano antimony trioxide: cinese antimony, Inc.;

25％KF/Al₂O₃: the self-made coating is prepared by adopting an impregnation method and a solid-phase grinding method, and is not repeated in the application for the prior art.

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 110-1.6 kg/cm of ethylene glycol and 0.1-0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²The esterification reaction is carried out by stirring at a constant speed under pressure, the esterification reaction time is controlled to be 3-5h, and the esterification reaction time is controlled to be 3-5h in the invention, because the side reaction is increased when the reaction time exceeds 5h, and the reaction time is less than 3 h, the water generated in the kettle can not be evaporated in time, the side reaction is increased, the melting point of PET is reduced when the side reaction is increased, and the appearance of the product is influenced; controlling the proportion of the terephthalic acid and the ethylene glycol within the range can reduce etherification reaction and the content of oligomers, the proportion is too small, which leads to incomplete esterification, after the unreacted terephthalic acid is introduced into a polycondensation kettle, a chain terminator is formed because most of the end group part of a macromolecular chain is carboxyl, thus macromolecular PET required by the process requirement can not be generated, if the proportion is too large, the etherification reaction is increased, which leads to the reduction of the melting point of the product,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than thatWhen the water yield of terephthalic acid and ethylene glycol is 98 percent of the theoretical and completely reflected water yield, 0.01 to 0.012 portion of antioxidant 618, 10 to 20 portions of third monomer and 0.02 to 0.03 portion of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-; KF/Al₂O₃The catalytic activity of the catalyst is mainly related to the alkali amount with medium strength, the medium alkalinity is beneficial to the polymerization reaction, the excessive alkali amount and strong alkali promote the thermal degradation reaction of PET, and the catalyst KF/Al₂O₃The active species in (A) is K₃AlF6, significantly reduced thermal degradation of PET, so the present invention uses 25% KF/Al₂O₃Compared with ethylene glycol antimony, the antimony trioxide added in the invention has lower use cost due to the reason of unit price and subsequent need of water removal, and can overcome the defects that the ethylene glycol antimony is very easy to absorb moisture and needs to be completely used up for 1 time after packaging and unsealing. In the pre-polycondensation stage, the concentration of reaction materials is low, and molecular chains are small, so that the vacuum degree is improved at a constant speed in the pre-polycondensation stage, so that liquid flooding caused by taking out a large amount of materials can be avoided;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet; the temperature and pressure of final polycondensation are controlled within the range, and the ethylene glycol can be extracted in time, so that the reaction time can be obviously shortened, and the viscosity and color value of the product are ensured;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3) and phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Example 1

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 110 parts of ethylene glycol and 0.1 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.01 part of antioxidant 618, 10 to 20 parts of third monomer and 0.02 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.2: 1.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the addition amount of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 0.002 percent of the mass of the PET original sheet, and the mass ratio of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 2:2: 1.

Example 2

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 110 parts of ethylene glycol and 0.15 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.011 part of antioxidant 618, 15 parts of third monomer and 0.05 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.2: 1.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the addition amount of the phosphate, the crown ether and the bisphenol internal alkyleneoxy compound is 0.005 percent of the mass of the PET original sheet, and the mass ratio of the phosphate, the crown ether and the bisphenol internal alkyleneoxy compound is 2:2: 1.

Example 3

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.15 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Constant under pressureStirring at high speed to perform esterification reaction for 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.011 part of antioxidant 618, 15 parts of third monomer and 0.025 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.32: 1.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the addition amount of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 0.01 percent of the mass of the PET original sheet, and the mass ratio of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 2:3: 1.

Example 4

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.15 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than that completely reflected by the theory of terephthalic acid and ethylene glycolWhen the content of the monomer is 98 percent, 0.012 part of antioxidant 618, 15 parts of third monomer and 0.025 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.32: 1.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the addition amount of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 0.02 percent of the mass of the PET original sheet.

Wherein the mass ratio of the phosphate, the crown ether and the bisphenol endoalkenyloxy compound is 2:3: 1.

Example 5

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.15 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.012 part of antioxidant 618, 15 parts of third monomer and 0.025 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for carrying outPre-polycondensation reaction, wherein the pre-polycondensation reaction temperature is 245-265 ℃, the vacuum degree is increased at a constant speed until the pressure is 1100-1200Pa, and the pre-polycondensation time is 30-40 min;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.32: 1.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the addition amount of the phosphate, the crown ether and the bisphenol endoalkenyloxy compound is 0.004 percent of the mass of the PET original sheet, and the mass ratio of the phosphate, the crown ether and the bisphenol endoalkenyloxy compound is 2:3: 1.

Example 6

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.012 part of antioxidant 618, 20 parts of third monomer and 0.025 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.32: 1.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the mass ratio of the phosphate, the crown ether and the bisphenol endoalkenyloxy compound is 2:3: 1.

Example 7

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.012 part of antioxidant 618, 20 parts of third monomer and 0.03 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.32: 1.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the addition amount of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 0.04 percent of the mass of the PET original sheet, and the mass ratio of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 2:3: 1.

Example 8

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.012 part of antioxidant 618, 20 parts of third monomer and 0.03 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, 25% KF/Al₂O₃And nano-scale trioxideThe mass ratio of antimony is 0.38: 1.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the addition amount of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 0.04 percent of the mass of the PET original sheet, and the mass ratio of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 2:4: 1.

Example 9

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.012 part of antioxidant 618, 20 parts of third monomer and 0.03 part of 25 percent KF/Al are added₂O₃Transferring the catalyst compounded with the nano antimony trioxide into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, 25% KF/Al₂O₃And the mass ratio of the nano antimony trioxide to the nano antimony trioxide is 0.5: 1.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the addition amount of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 0.05 percent of the mass of the PET original sheet, and the mass ratio of the phosphate, the crown ether and the bisphenol internal alkenyloxy compound is 2:5: 1.

Comparative example 1

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.012 part of antioxidant 618, 20 parts of third monomer and 0.025 part of 25 percent KF/Al are added₂O₃Transferring the catalyst into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the mass ratio of the phosphate, the crown ether and the bisphenol endoalkenyloxy compound is 2:3: 1.

Comparative example 2

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the nitrogen atmosphere at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, adding 0.012 part of antioxidant 618, 20 parts of third monomer and 0.025 part of nano antimony trioxide catalyst, transferring the mixture into a polycondensation kettle for pre-polycondensation reaction, wherein the pre-polycondensation reaction temperature is 245-;

3) and (3) final polycondensation reaction: increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain a PET (polyethylene terephthalate) raw sheet;

4) and (3) carrying out melt kneading on the PET original sheet obtained in the step (3), phosphate, crown ether and bisphenol endoalkenyloxy compound, wherein the melting temperature is 280 ℃, and the melting time is 5 min.

Wherein, the third monomer is selected from naphthalene dicarboxylic acid.

Wherein the mass ratio of the phosphate, the crown ether and the bisphenol endoalkenyloxy compound is 2:3: 1.

Comparative example 3

A synthetic method of polyester chips for low-extraction membranes comprises the following steps:

1) esterification reaction: 100 parts of terephthalic acid, 130 parts of ethylene glycol and 0.2 part of cobalt acetate are fully mixed and then transferred into a reaction kettle, the temperature is raised to 230 ℃ under the atmosphere of nitrogen at 1.2-1.6kg/cm²Stirring at constant speed under pressure to perform esterification reaction, controlling the esterification reaction time to be 3-5h,

2) pre-polycondensation reaction: when the water yield generated by the reaction is higher than 98 percent of the water yield completely reflected by the theory of terephthalic acid and ethylene glycol, 0.012 part of antioxidant 618, 20 parts of third monomer and 0.025 part of 25 percent KF/Al are added₂O₃The catalyst compounded with the nano antimony trioxide is transferred into a polycondensation kettle for pre-polycondensation reaction at the temperature of 245-The void degree to the pressure of 1100-1200Pa, and the pre-condensation time of 30-40 min;

3) and (3) final polycondensation reaction: and (3) increasing the vacuum degree at a constant speed, carrying out final polycondensation reaction under the vacuum degree of less than 110-120Pa, controlling the temperature of the final polycondensation reaction at 270-285 ℃, gradually reducing the stirring speed along with the increase of the viscosity, stopping the reaction when the intrinsic viscosity reaches 0.618dl/g, discharging the polymer to a cooling pool, and slicing to obtain the PET original sheet.

The PET chips from examples 1 to 9 and comparative examples 1 to 3 were weighed exactly 20g, and recorded as m₀Reflux-extracting for 24h in a Soxhlet extractor with xylene as solvent, spin-drying the extract, and weighing the extract mass as m ', m'/m₀The ratio of (a) to (b) is a xylene extraction value, and the xylene extraction values in examples 1 to 9 of the present invention are shown in table 1.

TABLE 1

	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6
							Xylene extract value (%)	0.58	0.52	0.45	0.44	0.41	0.36
	Example 7	Example 8	Example 9	Comparative example 1	Comparative example 2	Comparative example 3
							Xylene extract value (%)	0.44	0.41	0.45	0.69	0.71	0.73

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.