What material is polyester?

Polyester is a polymer material formed by polycondensation of polyhydric alcohol and polybasic acid.

Polyester mainly refers to polyethylene terephthalate (PET), and also includes linear thermoplastic resins such as polybutylene terephthalate (PBT) and polyarylate. It is an engineering plastic with excellent performance and wide application. It can also be made into polyester fiber and polyester film. Polyester includes polyester resin and polyester elastomer. Polyester is a polymer compound, which is polyethylene terephthalate (PET) condensed from terephthalic acid (PTA) and ethylene glycol (EG).

Polyester resins also include polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and polyarylate (PAR). Polyester elastomer (TPEE) is a thermoplastic elastomer, which is generally polymerized from dimethyl terephthalate, 1, 4- butanediol and polybutyl alcohol. The chain segment includes hard segment and soft segment.

Production method of polyester

High-purity terephthalic acid (PTA) is directly esterified with ethylene glycol or 1, 4- butanediol to produce dihydroxyethyl terephthalate or butyl ester, and then the polycondensation reaction is carried out. The key of this method is to solve the problem of uneven mixing of PTA with ethylene glycol or 1, 4- butanediol, improve the reaction speed and stop the etherification reaction. Compared with transesterification polycondensation, this method can save the steps of manufacturing, refining and methanol recovery of DMT, and it is easier to prepare polymers with large molecular weight and good thermal stability, which can be used to produce high-quality products such as tire cord.

Alternatively, ethylene oxide can be directly reacted with PTA to produce dihydroxyethyl terephthalate, and then polycondensation can be carried out. Its advantages are that the production process of synthesizing ethylene glycol from ethylene oxide can be omitted, the equipment utilization rate is high, the auxiliary equipment is few, and the product is easy to refine. The disadvantage is that the addition reaction between ethylene oxide and PTA needs to be carried out under the pressure of 2 ~ 3 MPa, which has strict requirements on equipment, thus affecting the wide use of this method.

The above contents refer to Baidu Encyclopedia-Polyester.