A kind of preparation method of polyester composition

Abstract

The invention discloses a preparation method of a polyester composition. In the method, an aromatic dicarboxylic acid and an aliphatic dihydric alcohol are subjected to an esterification reaction, and during the period from the end of the esterification reaction to the start of the polymerization reaction Add antimony compound, phosphorus-containing inorganic acid or phosphorus-containing organic compound, and alkali metal phosphate to the reaction system to start the polymerization reaction; during the period from the time when the intrinsic viscosity of the polymerization reactant reaches 0.5dl / g to the end of the polymerization reaction , add manganese compound to the reaction system, and continue the polymerization reaction until it is completed. The polyester composition prepared by the method has a gel rate of less than 5wt% after heat treatment at 300°C×6hr under a mixed gas of nitrogen / oxygen with an oxygen concentration of 1 vol%, and less foreign matter, and can be used for making films, fibers, etc. .

Description

Technical field[0001]The present invention relates to a preparation method of a polyester composition having a low gel and a small foreign matter.Background technique[0002]Polyester, especially polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, etc., is widely used due to excellent mechanical, physical and chemical properties Production of fibers, films and other molded products. However, most of the polyester will thermal oxygen degradation and thermal decomposition under high temperature conditions, in the thermal oxygen degradation reaction, oxygen free radicals from hydrogen on the polyester phenyl ring, forming a peroxidation functional group, the peroxidation functional group is unstable It also decomposes the generated free radical, the generated free radical as the product generated frame bridge structure after the frame bridge and the polyester thermal decomposition, that is, crosslinking reaction, forming a non-melting rubber, generally ref...

AI Technical Summary

Problems solved by technology

For example, Japanese Patent Laid-Open 2005-314643 and Japanese Patent Laid-Open 2006-225621 describe that gelation can be suppressed to some extent by adding titanium compounds in processes such as transesterification, but the heat resistance of polyester itself is reduced. Thermal cracking will occur during long-term film production, so gel formation cannot be sufficiently suppressed

At the same time, a stabilizer phosphorus compound is generally added during the polymerization process, and after the added phosphorus compound reacts with the metal co-catalyst, it is easy to form insoluble matter in the polyester and form particles, which will cause the filter pressure of the filter to rise during the molding process. It is easy to break during spinning, which will affect the spinning performance, or cause the filter pressure of the filter to increase during the membrane production process, and the filter will be replaced frequently, resulting in waste of raw materials and an increase in cost

In addition, the occurrence of gel defects on the film leads to a decrease in the quality of the film and limits its use

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