阅读说明：本技术 聚丙烯腈基碳纤维原丝废丝的回收方法 (Method for recovering waste silk of polyacrylonitrile-based carbon fiber precursor ) 是由 吴明金 万晓军 陈刚 张晓东 肖建文 廉信淑 于 2019-02-03 设计创作，主要内容包括：本发明提供了一种聚丙烯腈基碳纤维原丝废丝的回收方法。该回收方法包括：使聚丙烯腈基碳纤维原丝废丝在溶剂中溶解,得到纺丝液,溶剂为N,N-二甲基甲酰胺水溶液。通过溶解的方式将聚丙烯腈基碳纤维原丝废丝溶解在溶剂中形成纺丝液,形成的纺丝液作为其它工艺的原料,从而实现了对聚丙烯腈基碳纤维原丝废丝的回收利用。同时采用N,N-二甲基甲酰胺水溶液作为溶剂能够在单一的温度下就能够完成上述溶解过程,从而简化了回收工艺。因而采用上述回收方法极大地减少了聚丙烯腈基碳纤维原丝生产中的浪费,降低生产成本,并能够减少聚丙烯腈基碳纤维制备工艺对环境的污染。(The invention provides a method for recovering waste silk of polyacrylonitrile-based carbon fiber precursors. The recovery method comprises the following steps: dissolving polyacrylonitrile-based carbon fiber precursor waste filaments in a solvent to obtain a spinning solution, wherein the solvent is an N, N-dimethylformamide aqueous solution. The polyacrylonitrile-based carbon fiber precursor waste filament is dissolved in a solvent in a dissolving mode to form a spinning solution, and the formed spinning solution is used as a raw material of other processes, so that the polyacrylonitrile-based carbon fiber precursor waste filament is recycled. Meanwhile, the N, N-dimethylformamide aqueous solution is used as a solvent, so that the dissolving process can be completed at a single temperature, and the recovery process is simplified. Therefore, the recovery method greatly reduces the waste in the production of the polyacrylonitrile-based carbon fiber protofilament, reduces the production cost and can reduce the pollution of the polyacrylonitrile-based carbon fiber preparation process to the environment.)

1. A method for recovering waste polyacrylonitrile-based carbon fiber precursor filaments is characterized by comprising the following steps: and dissolving the polyacrylonitrile-based carbon fiber precursor waste silk in a solvent to obtain a spinning solution, wherein the solvent is an N, N-dimethylformamide aqueous solution.

2. The recovery method according to claim 1, wherein the weight ratio of the polyacrylonitrile-based carbon fiber precursor waste filaments to the solvent is 1 (3.5-4.5).

3. The recovery method according to claim 1 or 2, wherein the concentration of N, N-dimethylformamide in the solvent is not less than 96 wt%.

4. The recycling method according to claim 3, wherein the temperature of the dissolving process is 60-80 ℃ and the dissolving time is 2-6 h.

5. The recycling method according to claim 4, further comprising: the dissolution process was carried out under stirring.

6. The recycling method according to claim 5, wherein the stirring speed in the stirring process is 20 to 150 rpm.

7. The recovery method according to any one of claims 1 to 6, wherein before the dissolution process, the recovery method further comprises: and cutting the waste polyacrylonitrile-based carbon fiber precursor filaments.

8. The recycling method according to claim 7, wherein the length of the waste polyacrylonitrile-based carbon fiber strand is less than or equal to 2cm after the shearing process.

Technical Field

The invention relates to the field of carbon fiber preparation, in particular to a method for recovering waste polyacrylonitrile-based carbon fiber precursor filaments.

Background

In the production process of the polyacrylonitrile-based carbon fiber, high-quality polyacrylonitrile precursor is the premise for preparing qualified carbon fiber. The polyacrylonitrile protofilament is prepared from polyacrylonitrile polymer solution through the processes of solidification forming, coagulation bath drafting, washing, hot water drafting, oiling, steam drafting, steam shaping and the like, physical drafting runs through all the time in the whole process, and linear macromolecular chains are preferentially oriented along the fiber axis direction in the whole process. However, how to effectively relate the technical indexes of the precursor to the quality indexes of the carbonization production process and the final carbon fiber product is still a great problem which troubles production and researchers in the field. Therefore, the quality of the protofilament or whether the qualified carbon filament can be obtained can be known only after carbonization treatment, and the unqualified protofilament can be judged as waste filament only by losing the original value. In addition, in the production process of the protofilament, a large amount of waste silk is generated due to the factors of periodical starting and stopping operations of replacing a filter, replacing a spinneret plate and a device, broken silk, substandard indexes and the like. Because the polyacrylonitrile protofilament can not be depolymerized, thermoplastically processed, can not be used as fuel, and can only be treated as solid waste, at present, the price of the initial raw material acrylonitrile for producing the polyacrylonitrile protofilament reaches 1.9 ten thousand yuan/ton, the production cost per ton protofilament reaches more than 5 ten thousand yuan/ton, and the waste protofilament is treated as waste to cause great waste.

Disclosure of Invention

The invention mainly aims to provide a method for recycling polyacrylonitrile-based carbon fiber precursor waste filaments, which solves the problem that the existing method for treating the polyacrylonitrile-based carbon fiber precursor waste filaments cannot recycle the polyacrylonitrile-based carbon fiber precursor waste filaments.

In order to achieve the purpose, the invention provides a method for recovering waste polyacrylonitrile-based carbon fiber precursor filaments, which comprises the following steps: dissolving polyacrylonitrile-based carbon fiber precursor waste filaments in a solvent to obtain a spinning solution, wherein the solvent is an N, N-dimethylformamide aqueous solution.

Furthermore, the weight ratio of the polyacrylonitrile-based carbon fiber precursor waste silk to the solvent is 1 (3.5-4.5).

Furthermore, the concentration of the N, N-dimethylformamide in the solvent is more than or equal to 96 wt%.

Further, the recovery method further comprises: the dissolution process was carried out under stirring.

Furthermore, the temperature in the dissolving process is 60-80 ℃, and the dissolving time is 2-6 h.

Further, the stirring speed in the stirring process is 20-150 revolutions per minute.

Further, before the dissolution process, the recovery method further comprises: and (4) cutting the polyacrylonitrile-based carbon fiber precursor waste filaments.

Further, the length of the polyacrylonitrile-based carbon fiber precursor waste filament is less than or equal to 2cm through the shearing process.

By applying the technical scheme of the invention, the polyacrylonitrile-based carbon fiber precursor waste filament is dissolved in the solvent in a dissolving mode to form the spinning solution, and the formed spinning solution is used as a raw material of other processes, so that the polyacrylonitrile-based carbon fiber precursor waste filament is recycled. Meanwhile, the N, N-dimethylformamide aqueous solution is used as a solvent, so that the dissolving process can be completed at a single temperature, and the recovery process is simplified. Therefore, the recovery method greatly reduces the waste in the production of the polyacrylonitrile-based carbon fiber protofilament, reduces the production cost and can reduce the pollution of the polyacrylonitrile-based carbon fiber preparation process to the environment.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

The term "waste silk of polyacrylonitrile-based carbon fiber precursor" in the present application refers to unqualified polyacrylonitrile-based carbon fiber precursors.

As described in the background art, the existing polyacrylonitrile-based carbon fiber precursor waste silk treatment method cannot recycle the polyacrylonitrile-based carbon fiber precursor waste silk. In order to solve the technical problem, the application provides a method for recovering waste polyacrylonitrile-based carbon fiber precursor filaments, which comprises the following steps: dissolving polyacrylonitrile-based carbon fiber precursor waste filaments in a solvent to obtain a spinning solution, wherein the solvent is an N, N-dimethylformamide aqueous solution.

In the recovery method provided by the application, the polyacrylonitrile-based carbon fiber precursor waste filaments are dissolved in the solvent in a dissolving mode to form the spinning solution, and the formed spinning solution is used as a raw material of other processes, so that the polyacrylonitrile-based carbon fiber precursor waste filaments are recycled. Meanwhile, the N, N-dimethylformamide aqueous solution is used as a solvent, so that the dissolving process can be completed at a single temperature, and the recovery process is simplified. Therefore, the recovery method greatly reduces the waste in the production of the polyacrylonitrile-based carbon fiber protofilament, reduces the production cost and can reduce the pollution of the polyacrylonitrile-based carbon fiber preparation process to the environment.

Preferably, the dissolution process of the polyacrylonitrile-based carbon fiber precursor waste filaments can be directly merged into a precursor production system, the dissolved polymer can be used as a spinning solution for precursor spinning, a solvent used for dissolution can also enter a solvent recovery unit along with the precursor production system, and the economic benefit is obvious.

By adopting the recovery method, the waste in the production of the polyacrylonitrile-based carbon fiber precursor can be reduced, the production cost can be reduced, and the pollution of the preparation process of the polyacrylonitrile-based carbon fiber precursor to the environment can be reduced. In a preferred embodiment, the weight ratio of the polyacrylonitrile-based carbon fiber precursor waste silk to the solvent is 1 (3.5-4.5). The weight ratio of the polyacrylonitrile-based carbon fiber precursor waste filaments to the solvent includes but is not limited to the above range, and the restriction of the weight ratio to the solvent in the above range is favorable for further improving the dissolution rate of the polyacrylonitrile-based carbon fiber precursor waste filaments, thereby being favorable for improving the recovery efficiency of the polyacrylonitrile-based carbon fiber precursor waste filaments. Optionally, the weight ratio of the polyacrylonitrile-based carbon fiber precursor waste silk to the solvent is 1:3.5, 1:3.8, 1:4 and the like.

Preferably, when the solvent is an aqueous solution of N, N-dimethylformamide, the content of N, N-dimethylformamide is 96 wt% or more. The solvent with the concentration can improve the dissolving efficiency of the waste polyacrylonitrile-based carbon fiber precursor filaments.

In the above recovery method, the temperature and dissolution time in the dissolution process can be adjusted as required. In a preferred embodiment, the temperature of the dissolving process is 60-80 ℃, and the dissolving time is 2-6 h. Temperature and time of the dissolving process are limited in the range, so that the dissolving rate of the waste polyacrylonitrile-based carbon fiber precursor filaments is improved, and meanwhile, the dissolving time can be limited in a reasonable range, so that the efficiency of the dissolving process is improved.

Preferably, the above recovery method further comprises: the dissolution process was carried out under stirring. The dissolution process is carried out under stirring, which is favorable for improving the contact area of the polyacrylonitrile protofilament waste silk and the solvent, thereby being favorable for shortening the time required by dissolution.

Preferably, the stirring speed in the stirring process is 20-150 revolutions per minute. The stirring rate of the stirring process includes, but is not limited to, the above range, and it is preferable to limit it to the above range to further improve the efficiency of the dissolving process.

In order to further improve the efficiency of the dissolution, preferably, the recovery method further comprises, before performing the dissolution process: and (4) cutting the polyacrylonitrile-based carbon fiber precursor waste filaments. Before the polyacrylonitrile-based carbon fiber precursor waste silk and the solvent are subjected to the dissolving process, the polyacrylonitrile-based carbon fiber precursor waste silk is cut short, so that the contact area between the polyacrylonitrile-based carbon fiber precursor waste silk and the solvent is favorably increased, and the dissolving efficiency is favorably further improved. More preferably, the length of the waste polyacrylonitrile-based carbon fiber precursor filament is less than or equal to 2cm through the shearing process.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.