Method for efficiently preparing polytrimethylene terephthalate (PTT)

Abstract

The invention relates to a method for efficiently preparing polytrimethylene terephthalate (PTT). In the process of preparing the polytrimethylene terephthalate (PTT) from terephthalic acid and 1,3-propylene glycol through esterification, pre-polymerization and condensation polymerization reactions, the polytrimethylene terephthalate (PTT) is efficiently prepared by taking a MxTiyOz compound as acatalyst through catalysis. In the catalyst, metal M is an IIA element, the molar ratio of M represented as x to titanium represented as y is (1:5)-(5:1), a compound of titanate and the M is added into a diol solution, a reaction is carried out for 0.5-10 hours at 0-150 DEG C, after filtration washing and drying are carried out, calcination is carried out for 1-7 hours at 350-700 DEG C, and the polytrimethylene terephthalate (PTT) is obtained. The PTT is prepared by using the catalyst, which shortens the time of esterification and condensation polymerization, improves the intrinsic viscosity of the PTT and reduces the hue b value, the intrinsic viscosity of the PTT product is 0.91-1.15 dl / g, the b value is less than 3.0, and industrial application prospects are good.

Description

technical field [0001] The invention belongs to the field of catalytic reaction engineering, and relates to a method for efficiently preparing polytrimethylene terephthalate (PTT), in particular, it involves using Ti and IIA group bimetallic compounds as catalysts to efficiently catalyze terephthalic acid and 1 , A method for preparing polytrimethylene terephthalate (PTT) from 3-propanediol through esterification, prepolymerization, and polycondensation. Background technique [0002] 1,3-propylene glycol terephthalate (Poly trimethylene terephthalate) is a kind of raw material that can be used as raw materials of terephthalic acid (PTA) and 1,3-propanediol (1,3-PDO) through esterification, prepolymerization and Polycondensation reaction can be used to prepare an aromatic polyester fiber that can be prepared by dimethyl terephthalate (DMT) and 1,3-PDO through transesterification, prepolymerization and polycondensation reaction, referred to as PTT, also known as 3GT . The un...

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Problems solved by technology

[0005] It can be seen that in the existing PTT process of PTA and 1,3-PDO polymerization, there are composite catalysts formed by compounding titanate and other compounds. This type of catalyst is easy to hydrolyze to form TiO 2 Hydrates make it difficult to disperse into the reactants, and at the same time cause a decrease in catalyst activity and an increase in dosage; and titanate is easy to make PTT polyester yellow, and the hue b value is relatively high

In addition, due to the long reaction time of some catalysts, stabilizers or antioxidants need to be added, and more acrolein is likely to be produced during the polycondensation process. The content of carboxyl groups in PTT products is high, which affects the quality of PTT products.

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