Method for making polyester for manufacturing industrial silk

Abstract

A preparation method for manufacturing industrial yarn polyester comprises the processes that terephthalic acid can esterify ethylene glycol under the temperature of 250 DEG C to 275 DEG C to produce the intermediate of dihydroxy ethyl terephthalate, the reaction lasts to the esterification rate with at least 92 percent, and the water produced during the reaction is removed; the intermediate of dihydroxy ethyl terephthalate is carried out the polycondensation under the presence of a catalyst system and the condition of negative pressure to obtain polyester products, the polycondensation temperature is 270 DEG C to 291 DEG C, the reaction lasts 2 to 3 hours, and the catalyst system contains glycol antimony and molybdenum trioxide. The catalyst dosage is based on the theoretical yield of the polyester obtained by the polycondensation; wherein, the glycol antimony dosage by antimony ions is 250 to 320ppm; the molybdenum trioxide by molybdenum ions is 5 to 30ppm. The preparation method has the advantages that the carboxyl end group content of the polyester product is lower, the solid-phase polycondensation time is shortened, the spinning melt uniformity is higher, and the heat resistance of the manufactured industrial yarn product is greatly improved.

Description

technical field [0001] The invention relates to a method for producing polyester, in particular to a method for producing polyester for industrial yarns by using terephthalic acid and ethylene glycol as monomers. The catalyst system used in the polycondensation reaction contains ethylene glycol antimony and trioxide molybdenum. Background technique [0002] With the development of the economy, the demand for polyester industrial yarn is increasing day by day, and polyester fiber has been widely used in the fields of automobile, construction, water conservancy and transportation. Polyester industrial filaments usually refer to high-strength, coarse-denier filament fibers whose denier is equal to or greater than 550dtex. In order to obtain higher strength, the method of solid-phase thickening is generally used to further increase the molecular weight of polyester obtained by conventional esterification and polycondensation processes, and the molecular weight of the final poly...

AI Technical Summary

Problems solved by technology

Generally, the carboxyl group content of polyester is 30-35%, which not only leads to thermal degradation in the spinning process, but also makes the heat resistance of the final fiber product decrease due to the high carboxyl group content.

In the prior art, prolonging the time of solid-state polymerization is usually used to reduce the content of carboxyl-terminated polyesters used for spinning, but this in turn increases the probability of thermal degradation during solid-state polymerization