[Chemical Knowledge]：Manufacturing method and process of polyester

Manufacturing method
of polyester
Polyester (Polyester) is an important chemical product, which is widely used in fiber, film, container, insulation material and other fields. This article will introduce the manufacturing method of polyester, including raw material preparation, esterification reaction, polycondensation reaction, post-treatment and other steps.

1. Raw Material Preparation
The manufacture of
polyesters requires two primary raw materials: dibasic acids and glycols. Commonly used dibasic acids include terephthalic acid (TPA), isophthalic acid (IPA), and the like, and commonly used dihydric alcohols include ethylene glycol (EG), propylene glycol (PG), and the like. These raw materials are commercially available.

2. Esterification

Esterification is the process of reacting a dibasic acid with a diol to form an ester. The esterification reaction generally uses a batch reactor, the reaction temperature is 200-250 degrees C, the reaction pressure is 0.1-0.5MPa. In the esterification reaction, a catalyst needs to be added, and commonly used catalysts include p-toluenesulfonic acid, sulfuric acid, etc. The water produced by the esterification reaction needs to be discharged from the reactor in time to keep the reaction going.

3. polycondensation

polycondensation is the process of further reacting an ester to form a polyester. The polycondensation reaction generally uses a continuous reactor, the reaction temperature is 250-300 degrees C, the reaction pressure is 0.1-1MPa. In the polycondensation reaction, a catalyst and a stabilizer need to be added. Commonly used catalysts include tetrabutyl titanate, antimony acetate, etc., and commonly used stabilizers include tricresyl phosphate, triphenyl phosphite, etc. The water generated by the polycondensation reaction needs to be discharged from the reactor in time, and the vacuum degree of the reactor needs to be controlled to maintain the reaction.

4. post-treatment
After the
polycondensation reaction is completed, post-treatment is required, including pelletizing, drying, packaging and other steps. Cutting is to cut polyester into a certain length of particles, convenient for subsequent processing and use. Drying is to remove the moisture in the polyester particles to ensure its quality. Packaging is to pack the dried polyester particles for storage and transportation.

In short, the production of polyester requires the steps of raw material preparation, esterification reaction, polycondensation reaction and post-treatment. In the production process, it is necessary to strictly control the reaction conditions and the quality of raw materials to ensure the quality and output of polyester. At the same time, it is also necessary to strengthen the maintenance and maintenance of production equipment to ensure the stable operation of the production line.

5. quality control and environmental protection requirements

In the production process of polyester, it is necessary to pay attention to product quality control and environmental protection requirements. For quality control, it is necessary to establish a sound quality management system to ensure that product quality meets relevant standards and customer requirements. For environmental protection requirements, it is necessary to take effective measures to reduce the discharge of waste gas, waste water and solid waste in the production process, strengthen waste water treatment and waste gas treatment, and reduce the impact on the environment.

6. technology innovation and development trend

With the continuous progress of science and technology, the production technology of polyester is also constantly innovating and developing. In the future, the production of polyester will pay more attention to environmental protection, efficiency and sustainable development, and continue to promote technological innovation and product upgrades. At the same time, with the continuous emergence of new materials, the application field of polyester will continue to expand, injecting new vitality into the development of chemical production raw materials.

In short, the manufacturing method of polyester involves multiple links and processes, and it is necessary to strictly control the production conditions and the quality of raw materials, and pay attention to product quality control and environmental protection requirements. In the future, with the continuous innovation and development of technology, the production of polyester will be more efficient, environmentally friendly and sustainable, and make greater contributions to the development of chemical production raw materials.