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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 provide a detailed introduction to the manufacturing methods of polyester resin, including raw material preparation, esterification reaction, condensation reaction, post-treatment, and other processes

2、 Raw material preparation 

1 Dicarboxylic acid: Commonly used are aromatic dicarboxylic acids such as adipic acid and terephthalic acid, with a purity of over 99%

2. Diols: Commonly used are aliphatic diols such as ethylene glycol and propylene glycol, and their purity should also be higher than 99%

3. Catalysts: Titanium based catalysts such as tetrabutyl titanate and tetraisopropyl titanate are usually used

4. Polymerization inhibitor: To prevent self polymerization of polyester resin during the manufacturing process, an appropriate amount of polymerization inhibitor, such as hydroquinone, needs to be added

3、 Esterification reaction: Add a certain molar ratio of dicarboxylic acid and diols to the reaction vessel, add an appropriate amount of catalyst and polymerization inhibitor, and raise the temperature to 180-220 ℃ for esterification reaction. This reaction is an exothermic reaction, and the reaction temperature needs to be controlled to avoid local overheating. The water generated during the reaction process needs to be discharged in a timely manner to maintain the acidity of the reaction system. The esterification reaction generally takes 4-6 hours

4、 After the completion of the esterification reaction, the temperature is lowered to 160-180 ℃, and an appropriate amount of condensation catalyst, such as antimony trioxide, is added to carry out the condensation reaction. Polycondensation reaction is the process of gradually polymerizing low molecular weight polyester produced by esterification reaction into high molecular weight polyester by removing small molecule by-products (such as water, alcohol, etc.). The condensation reaction requires a high degree of vacuum in order to timely discharge by-products and promote the progress of the reaction. The condensation reaction generally takes 6-8 hours

5、 After the completion of post-processing 

condensation reaction, cool down to room temperature, discharge the polyester resin, and perform granulation or granulation treatment. The obtained polyester resin particles need to be dried to remove moisture and other low molecular by-products. The dried polyester resin particles can be used for subsequent processing and molding processes

6、 Notes 

1 The purity of raw materials has a significant impact on the performance of polyester resin, so high-purity raw materials are needed

2. Temperature and vacuum control are required during esterification and condensation reactions to avoid side reactions and ensure the molecular weight of the product

During the post-processing, attention should be paid to drying to avoid the influence of moisture and other low molecular weight by-products in the product on the subsequent processing and molding process

7、 Conclusion: The manufacturing method of polyester resin includes processes such as raw material preparation, esterification reaction, condensation reaction, and post-treatment. By controlling the reaction conditions and post-treatment process, high-performance polyester resin products can be obtained.