Method for preparing polyester

Abstract

The invention provides a method for preparing polyester. The method comprises the following steps of: firstly stirring and mixing organic titanate, a hydrophilic polymer and dibasic alcohol to prepare a hydrolysis-resistant titanium catalyst by taking dibasic acid and the dibasic alcohol as main reaction raw materials; then carrying out the steps of blending, esterification, polycondensation, and the like to prepare a polyester product. Compared with the traditional method for catalytically synthesizing the polyester product by adopting the organic titanate, the method provided by the invention has the advantages that prepared polyester products, namely PBT (Polybutylece Terephthalate) and the like, are corresponding in conventional property and the hydrolysis-resistant titanium catalyst difficultly loses activity through hydrolysis and shows higher catalytic activity.

Description

technical field [0001] The invention relates to a preparation method of polyester, especially suitable for the preparation method of polybutylene terephthalate. Background technique [0002] Polyester, a general term for polymers obtained by polycondensation of polyols and polybasic acids, mainly includes polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and polyarylate (PAR). Among them, PBT (polybutylene terephthalate), PE (polyethylene), PC (polycarbonate), POM (polyoxymethylene), PA (polyamide), etc. are called the five general-purpose engineering plastics. In particular, PBT (polybutylene terephthalate) is a product with rapid development, rapid growth in production capacity, multiple specifications and a wide range of applications. Because PBT has good properties such as heat resistance, weather resistance, chemical resistance, good electrical properties, low water absorption, and good gloss, PBT is not only widely used in electronic appliances, auto ...

AI Technical Summary

Problems solved by technology

[0004] However, there are certain defects in titanate. Due to the characteristics of titanate compounds, titanate catalysts can easily interact with water generated in the reaction system to form hydrolyzate, which not only reduces the catalytic efficiency, but also easily deposits and blocks the pipeline, causing serious problems. production inconvenience

[0005] Chinese patent CN1130645 discloses that tetrabutyl titanium is used as a catalyst, and phosphate or phosphite is used as a stabilizer to participate in the synthesis of PBT. As mentioned above, the tetrabutyl titanium used has poor hydrolysis resistance.

[0006] Japanese patents JP2002143930 and JP2003176531 disclose the preparation method of PBT using organic titanate and organic tin as catalysts, but there are still disadvantages of poor hydrolysis resistance of catalysts

[0007] Chinese patent CN101253217 discloses that the catalyst used in the synthesis of PBT is a composition comprising a titanium compound and at least one other alkaline earth metal ion compound. Although the catalyst has certain hydrolysis resistance, the operation steps are cumbersome in the actual process and the production cost is high. higher

[0008] Chinese patent CN1358207 discloses that the catalyst tetrabutyl titanate used in the synthesis of PBT also has the disadvantage of poor hydrolysis resistance of the catalyst

[0009] Chinese patent CN1507465 discloses that the catalyst of the method for synthesizing PBT is titanate, and the method reveals that by adding dicarboxylic acid and / or hydroxycarboxylic acid and / or monohydroxyalkyl dicarboxylic acid as a stabilizer of titanate, to reduce titanic acid For the hydrolysis of ester catalysts, especially PBT can be used to prepare raw material TPA (terephthalic acid) as a stabilizer for titanate to avoid the increase of new by-products in the reaction system. Under the lower conditions, the stable system formed by the stabilizer and the titanate catalyst will be destroyed, thereby reducing the hydrolysis resistance and catalytic efficiency of the titanate