Preparation method of regenerated polyester fibers

Abstract

The invention discloses a preparation method of regenerated polyester fibers. The preparation method is used in the field of chemical regeneration of waste polyester. According to the method, a glycol titanium alkali metal coordination compound which can be dissolved in ethylene glycol is used as a catalyst for catalyzing ethylene glycol in a waste polyester product for depolymerization and a repolymerization process of depolymerized products; the catalyst is higher in catalysis activity in ethylene glycol depolymerization of polyester and the repolymerization process of the depolymerized products; therefore, in the preparation method of the regenerated polyester fibers, the catalyst is not required to be removed from the depolymerized products in a regenerated polyester fiber preparation process, and can be used for polycondensation, so that the depolymerized product separation and purification cost is greatly reduced, and the quality of regenerated polyester is guaranteed; the color and the intensity of the regenerated polyester fibers can be obviously improved, and continuous closed-loop recycling of the waste polyester product can be realized.

Description

technical field [0001] The invention belongs to the technical field of chemical regeneration of polyester, and relates to a preparation method of recycled polyester fiber, in particular to a method for using a dihydric alcohol titanium alkali metal coordination compound soluble in ethylene glycol as a catalyst for use in waste polyester fibers. The invention relates to a method for preparing regenerated polyester fibers obtained by depolymerizing ethylene glycol of ester products and recondensing spinning. Background technique [0002] Polyethylene terephthalate (PET, polyester for short) is a semi-crystalline thermoplastic polymer material with excellent performance, which is widely used in chemical fiber, packaging, medicine, electronic machinery and other fields. The number one variety of fiber. In 2010, the total global polyester production reached 56.1 million tons. With the rapid development of the polyester industry, the disposal of waste polyester products has come...

AI Technical Summary

Problems solved by technology

At present, the most well-known alcoholysis catalyst is a metal salt represented by zinc acetate. Although the alcoholysis catalytic efficiency of zinc acetate is high, zinc acetate has serious defects as a depolymerization catalyst. First, its dosage is relatively high, generally 0.5-1.5% of the PET mass, and it is difficult to remove from the product after depolymerization. At the same time, the high content of zinc ions remaining in the depolymerization product will cause thermal degradation during repolymerization due to its catalytic mechanism for carbonyl oxygen coordination. The side reaction is accelerated, which makes the growth of molecular weight limited, the viscosity of recycled polyester is low, the quality is poor, and the spinnability is poor

Invention patent CN 102584594 AC℃l42- / NiCl42-type ionic liquid catalyzed alcoholysis method of polyethylene terephthalate, invention patent CN 102731310 A first transition metal ionic liquid catalyzed alcoholysis of polyethylene terephthalate The method of alcohol ester, and CN200810101969.2 is used in the polyester alcoholysis catalyst announced in the catalyst of alcoholysis polyethylene terephthalate, although have mild reaction conditions, fast reaction speed, high conversion rate, The catalytic selectivity is high, the catalyst can be recycled, etc., but at the same time, there is a defect that cannot be ignored, that is, the content of halogen elements in the catalyst of this type of ionic liquid is very high. If the catalyst cannot be removed from the depolymerization product, then the During the polymerization process, the generation of hydrogen halide will lead to the decomposition of macromolecules, which will seriously affect the quality of repolymerized products and make the recycled polyester lose its spinnability. The complete removal of the catalyst from the depolymerization products will greatly increase the production cost. The loss outweighs the gain

Invention patent CN200810126347.5 SO42- / MO2 type solid acid catalyst disclosed in the preparation of BHET (bishydroxyethyl terephthalate) by degrading polyethylene terephthalate with SO42- / MO2 type solid superacid catalyst Although it has the characteristics of easy separation of products, high catalytic selectivity, and easy recycling, because it is a heterogeneous catalyst, the mass transfer process in reaction catalysis is complicated, resulting in low catalytic efficiency.

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