Method for preparing fast-oxidized polyacrylonitrile fiber

Abstract

The invention relates to a method for preparing a fast-oxidized polyacrylonitrile fiber. The method comprises the following steps of: 1, uniformly mixing polyacrylonitrile powder with ionic liquid according to a weight ratio of 1: 0.25-1:1.8 to prepare a mixture, and introducing oxygen-containing gas at the temperature of 120-200 DEG C to carry out melt spinning to obtain a nascent filament; and 2, carrying out dry heat stretching on the nascent filament, extracting the stretched fiber at the temperature of 50-80 DEG C by using an extracting agent and finally carrying out heat-setting to obtain the polyacrylonitrile fiber, wherein the stretching temperature is 80-120 DEG C and total stretching multiple is 2-10. The method provided by the invention has a simple process and low cost, the prepared fiber can be uniformly oxidized, the skin core structure is reduced, the structure compactness of a carbon fiber is improved, the pre-oxidation rate is increased, the cost of the carbon fiber is reduced and the fast-oxidized polyacrylonitrile fiber has a good application prospect.

Description

technical field [0001] The invention belongs to the field of preparation of polyacrylonitrile fibers, in particular to a preparation method of rapidly oxidized polyacrylonitrile fibers. Background technique [0002] The pre-oxidation methods of carbon fiber precursor polyacrylonitrile precursors reported in the literature are all to pre-oxidize the precursors in air. That is, polyacrylonitrile-based carbon fibers are completed according to the three major processes of spinning, pre-oxidation, and carbonization, but there will be some disadvantages according to this process sequence: First, in the process of pre-oxidation of polyacrylonitrile precursors, if There is a gradient difference in the degree of pre-oxidation in the transverse section of the fiber, which causes uneven fiber morphology and structure. For example, the common skin-core structure will cause uneven shrinkage along the fiber radial direction on the fiber section, poor preferred orientation, and decreased t...

AI Technical Summary

Problems solved by technology

That is, polyacrylonitrile-based carbon fibers are completed according to the three major processes of spinning, pre-oxidation, and carbonization, but there will be some disadvantages according to this process sequence: First, in the process of pre-oxidation of polyacrylonitrile precursors, if There is a gradient difference in the degree of pre-oxidation in the transverse section of the fiber, which causes uneven fiber morphology and structure. For example, the common skin-core structure will cause uneven shrinkage along the fiber radial direction on the fiber section, poor preferred orientation, and decreased tensile properties. The performance of the final carbon fiber decreases; secondly, the pre-oxidation process takes a long time, the temperature is high, and the pre-oxidation process equipment is complicated, which increases the cost of the pre-oxidation process, resulting in a significant increase in the cost of the entire carbon fiber production process

Shortening the pre-oxidation time is the key to reducing the production cost of carbon fiber, but the short time will aggravate the skin-core structure, and the carbonization stage is prone to produce large voids and defects, resulting in a decrease in the mechanical properties of carbon fiber

Reduce the pre-oxidation temperature and prolong the pre-oxidation time, the skin-core structure of the pre-oxidized fiber is not obvious, which is beneficial to improve the performance of carbon fiber, but reduces the production efficiency

Therefore, no excellent pre-oxidation process has been developed so far.

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