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[Chemical Knowledge]：Production method and process of polyester resin

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The manufacturing method
of polyester resin
1. Introduction

polyester resin is a synthetic resin widely used in the field of chemical production, with excellent physical properties and chemical stability. This article will introduce the manufacturing method of polyester resin in detail, including raw material preparation, esterification reaction, polycondensation reaction, post-treatment and other processes.

2. raw material preparation

1. dibasic acid: commonly used is adipic acid, terephthalic acid and other aromatic dibasic acid, its purity should be higher than 99%.
2. diols: commonly used are ethylene glycol, propylene glycol and other aliphatic diols, the purity should also be higher than 99%.
3. Catalyst: Usually, a titanium-based catalyst such as tetrabutyl titanate and tetraisopropyl titanate is used.
4. Polymerization inhibitor: In order to prevent the polyester resin from self-polymerization during the manufacturing process, an appropriate amount of polymerization inhibitor, such as hydroquinone, needs to be added.

3. Esterification Reaction

dibasic acid and diol in accordance with a certain molar ratio into the reaction kettle, adding an appropriate amount of catalyst and inhibitor, heating to 180-220 DEG C, esterification reaction. The reaction is exothermic and the reaction temperature needs to be controlled to avoid local overheating. The water produced during the reaction needs to be discharged in time to maintain the acidity of the reaction system. The esterification reaction typically requires 4-6 hours.

4. polycondensation reaction

After the esterification reaction is completed, the temperature is lowered to 160-180 ° C., and an appropriate amount of polycondensation catalyst, such as antimony trioxide, is added to carry out the polycondensation reaction. The polycondensation reaction is a process in which the low molecular weight polyester generated by the esterification reaction is gradually polymerized into a high molecular weight polyester by removing small molecular by-products (such as water, alcohol, etc.). The polycondensation reaction requires a high degree of vacuum in order to discharge the by-products in time and promote the reaction. The polycondensation reaction typically requires 6-8 hours.

5. post-treatment
After completion of the
polycondensation reaction, the temperature is lowered to room temperature, and the polyester resin is discharged and pelletized or granulated. The resulting polyester resin particles are subjected to a drying treatment to remove moisture and other low-molecular by-products therefrom. The dried polyester resin particles can be used in the subsequent processing and molding process.
Precautions for
6.

1. The purity of raw materials has a great influence on the performance of polyester resins, so high-purity raw materials are required.
2. Esterification reaction and polycondensation reaction process need to control the temperature and vacuum, in order to avoid the occurrence of side reactions and ensure the molecular weight of the product.
3. The post-treatment process should pay attention to drying treatment, in order to avoid the product of moisture and other low molecular by-products on the subsequent processing molding process.

7. Conclusion The manufacturing method of

polyester resin includes the steps of raw material preparation, esterification reaction, polycondensation reaction and post-treatment. By controlling the reaction conditions and post-treatment process, polyester resin products with excellent performance can be obtained.

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