阅读说明：本技术 一种再生聚酯纤维的制备方法 (Preparation method of regenerated polyester fiber ) 是由 方光明 方叶青 陈浩 于 2019-11-22 设计创作，主要内容包括：本发明提供了一种再生聚酯纤维的制备方法,包括以下步骤：A)将聚酯废料、引发剂和二元醇进行醇解,得到聚酯低聚物熔体；B)将所述聚酯低聚物熔体过滤后蒸发,以去除二元醇,再缩聚,得到聚酯熔体；C)将所述聚酯熔体纺丝,得到再生聚酯纤维。本申请提供了一种再生聚酯纤维的制备方法,利用半醇解工艺得到了聚酯低聚物熔体,熔体聚合物下降,便于后续过滤除去内在的非聚酯和杂质,有利于得到纯度高的聚酯熔体,最终有利于提高再生聚酯纤维的品质。(The invention provides a preparation method of regenerated polyester fibers, which comprises the following steps: A) carrying out alcoholysis on the polyester waste, an initiator and dihydric alcohol to obtain a polyester oligomer melt; B) filtering the polyester oligomer melt, evaporating to remove dihydric alcohol, and performing polycondensation to obtain a polyester melt; C) and spinning the polyester melt to obtain the regenerated polyester fiber. The application provides a preparation method of regenerated polyester fibers, wherein a polyester oligomer melt is obtained by utilizing a semi-alcoholysis process, the melt polymer is reduced, the subsequent filtration is convenient for removing the inherent non-polyester and impurities, the polyester melt with high purity is favorably obtained, and the quality of the regenerated polyester fibers is favorably improved finally.)

1. A preparation method of a regenerated polyester fiber comprises the following steps:

A) carrying out alcoholysis on the polyester waste, an initiator and dihydric alcohol to obtain a polyester oligomer melt; the content of the dihydric alcohol is 30-60 wt% of the polyester waste;

B) filtering the polyester oligomer melt, evaporating to remove dihydric alcohol, and performing polycondensation to obtain a polyester melt;

C) and spinning the polyester melt to obtain the regenerated polyester fiber.

2. The method according to claim 1, wherein the content of the glycol is 40 to 50 wt% of the polyester waste.

3. The method according to claim 1, wherein the alcoholysis process comprises:

heating the polyester waste, the initiator and the dihydric alcohol to 200-300 ℃, reacting for 2-3 h, and cooling to 100-150 ℃ to obtain the polyester oligomer melt.

4. The method according to claim 1, wherein the polyester melt has a viscosity of 0.65 to 0.70dl/g and a purity of 95% or more.

5. The method according to claim 1, wherein the initiator is contained in an amount of 0.2 to 0.5 wt% based on the polyester waste.

6. The method according to any one of claims 1 to 5, wherein the diol is ethylene glycol.

Technical Field

The invention relates to the technical field of polyester waste regeneration, in particular to a preparation method of regenerated polyester fiber.

Background

Polyethylene terephthalate (polyester, PET for short) is a semi-crystalline polymer material, mainly used in the fields of textiles and plastics. There are differences in the characteristics of polyester raw materials for textiles and plastics: both have been used in parallel in terms of viscosity, molecular weight, crystallinity, transparency, and the like. With the wide application of polyester materials in the fields of textiles and plastics, waste textiles and waste polyester materials are more and more. In China, about 3000 million tons of waste textiles are produced every year, and about 100 million tons of waste polyester is low-value and low-quality polyester waste with miscellaneous color, low or high intrinsic viscosity distortion, low melting point and the like in 500 million tons of waste polyester bottle materials. Because the polyester waste has complex components and large characteristic difference, no advanced scientific method is available at present for realizing high-value recycling; it is very burdensome to the environment because of its non-degradability.

The regenerated polyester fiber is spun by using waste textiles (clothes mainly made of terylene, leftover materials and the like) and low-value and low-quality waste polyester, but the waste polyester has complex components, high impurity content and large intrinsic viscosity difference (0.5-0.9 dl/g). The conventional spinning method of the regenerated polyester fiber is a pure physical method of sorting, crushing, cleaning, dehydrating and drying the regenerated polyester, and obviously, the physical method cannot remove the intrinsic non-polyester components and can not adjust the intrinsic viscosity. Currently, the preparation of the regenerated polyester fiber generally adopts an alcoholysis method, i.e. glycol is adopted to carry out alcoholysis on the polyester waste, but the addition amount of glycol has a great influence on the alcoholysis of the polyester waste: the micro-addition of ethylene glycol (0.5%) for the micro-alcoholysis of the regenerated polyester can only play a role in filtering and removing external impurities and fine-tuning the intrinsic viscosity; the method for carrying out full alcoholysis on the old polyester by adding ethylene glycol which is several times (2-8 times) as much as the raw material can prepare high-purity polyester melt by carrying out complete depolymerization, filtration, esterification and polymerization on the old polyester, but the method has high cost and complex process. Therefore, the search for a proper alcoholysis method has great significance for spinning the regenerated polyester fiber.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a preparation method of the regenerated polyester fiber, which ensures that the purity of polyester melt is high, and the high-quality regenerated polyester fiber can be spun.

In view of the above, the present application provides a method for preparing a recycled polyester fiber, comprising the steps of:

A) carrying out alcoholysis on the polyester waste, an initiator and dihydric alcohol to obtain a polyester oligomer melt; the content of the dihydric alcohol is 30-60 wt% of the polyester waste;

B) filtering the polyester oligomer melt, evaporating to remove dihydric alcohol, and performing polycondensation to obtain a polyester melt;

C) and spinning the polyester melt to obtain the regenerated polyester fiber.

Preferably, the content of the dihydric alcohol is 40-50 wt% of the polyester waste.

Preferably, the alcoholysis process specifically comprises:

heating the polyester waste, the initiator and the dihydric alcohol to 200-300 ℃, reacting for 2-3 h, and cooling to 100-150 ℃ to obtain the polyester oligomer melt.

Preferably, the viscosity of the polyester melt is 0.65-0.70 dl/g, and the purity is more than 95%.

Preferably, the content of the initiator is 0.2-0.5 wt% of the polyester waste.

Preferably, the glycol is ethylene glycol.

The application provides a preparation method of a regenerated polyester fiber, which comprises the steps of carrying out alcoholysis on polyester waste, an initiator and dihydric alcohol, wherein the dosage of the dihydric alcohol is only 30-60 wt%, the alcoholysis is a semi-depolymerization technology and is between micro-alcoholysis and full alcoholysis, the alcoholysis technology obtains a polyester oligomer melt, the polymerization degree of the melt is reduced, the subsequent filtration is convenient to remove inherent non-polyester and impurities, the polyester melt with high purity is favorably obtained, and the quality of the regenerated polyester fiber is favorably improved finally.

Drawings

FIG. 1 is a schematic view of the process for preparing the regenerated polyester fiber of the present invention.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

In view of the current situation that alcoholysis affects the performance of the regenerated polyester fiber in the preparation process of the regenerated polyester fiber in the prior art, the application provides a preparation method of the regenerated polyester fiber, and the method realizes purification of polyester melt by utilizing a semi-depolymerization mode, and finally ensures the quality of the regenerated polyester fiber. Specifically, the embodiment of the invention discloses a preparation method of a regenerated polyester fiber, which comprises the following steps:

A) carrying out alcoholysis on the polyester waste, an initiator and dihydric alcohol to obtain a polyester oligomer melt; the content of the dihydric alcohol is 30-60 wt% of the polyester waste;

B) filtering the polyester oligomer melt, evaporating to remove dihydric alcohol, and performing polycondensation to obtain a polyester melt;

C) and spinning the polyester melt to obtain the regenerated polyester fiber.

In the preparation method of the regenerated polyester fiber, firstly, polyester waste, an initiator and dihydric alcohol are subjected to alcoholysis to obtain a copolyester oligomer melt; in this process, the polyester waste may be selected from well-known polyester waste such as waste polyester bottle chips, cloth, or waste films, and is not particularly limited in this application. The addition amount of the initiator is 0.2-0.5 wt% of the polyester waste, and the initiator is well known to those skilled in the art and can be selected from one or more of alkali metals and metal salts. The glycol is selected from ethylene glycol in specific embodiments. The using amount of the dihydric alcohol is 30-60 wt% of the polyester waste, and in a specific embodiment, the using amount of the dihydric alcohol is 40-50 wt% of the polyester waste.

The alcoholysis process comprises the following steps: heating the polyester waste, the initiator and the dihydric alcohol to 200-300 ℃, reacting for 2-3 h, and cooling to 100-150 ℃ to obtain the polyester oligomer melt. Because the using amount of the dihydric alcohol is 30-60 wt% of the polyester waste, the alcoholysis is a semi-depolymerization process which is between micro-alcoholysis and full alcoholysis, and the depolymerization mode enables the polyester waste to obtain a polyester oligomer melt after alcoholysis, so that the polymerization degree of the melt is reduced, and the subsequent filtration is facilitated to remove internal non-polyester substances and impurities.

The polyester oligomer melt is then filtered to remove 15 μm or more of insoluble matter, filtered and then evaporated to remove glycol. According to the invention, the obtained melt is then subjected to polycondensation to obtain a polyester melt; the filtration, evaporation and polycondensation are all technical means well known to those skilled in the art, and the specific embodiments thereof are not particularly limited in this application. The polycondensation is preferably carried out in a polycondensation vessel, during which a vacuum is applied to 50 Pa. The purity of the polyester melt is more than 95%, and the viscosity is 0.65-0.70 dl/g.

According to the invention, the polyester melt is finally spun to obtain the regenerated polyester fiber; the technical means of said spinning are well known to those skilled in the art and no particular limitation is imposed on this application.

The application provides a preparation method of regenerated polyester fibers, a specific flow schematic diagram is shown in fig. 1, in the method, the addition amount of dihydric alcohol is adjusted, so that alcoholysis is a semi-alcoholysis process, a polyester oligomer melt is obtained firstly, the polymerization degree of the melt is reduced, non-polyester and impurities in the melt are conveniently removed, the purity of the polyester melt is ensured, and finally the improvement of the quality of the regenerated polyester fibers is facilitated.

For further understanding of the present invention, the following examples are provided to illustrate the preparation method of the recycled polyester fiber provided by the present invention, and the scope of the present invention is not limited by the following examples.