Method for preparing fast-oxidized polyacrylonitrile fiber

A technology of polyacrylonitrile fiber and polyacrylonitrile powder, which is applied in the field of preparation of polyacrylonitrile fiber, can solve the problems of reducing the pre-oxidation temperature, reducing the mechanical properties of carbon fiber, and increasing the skin-core structure, so as to improve the pre-oxidation speed and reduce the The cost of carbon fiber, the effect of improving the compactness of the structure

Inactive Publication Date: 2013-05-08
DONGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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.

Method used

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  • Method for preparing fast-oxidized polyacrylonitrile fiber
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  • Method for preparing fast-oxidized polyacrylonitrile fiber

Examples

Experimental program
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Effect test

Embodiment 1

[0026] Mix the dried polyacrylonitrile and 1-butyl-3-methylimidazolium chloride salt ionic liquid uniformly at a ratio of 1:1.8, add the mixture into the twin-screw and simultaneously feed air into the twin-screw for spinning, The spinning temperature was 160°C, and the winding speed thereof was 400 m / min. The spun spun silk is directly stretched by dry heat, the stretching temperature is 120°C, and the stretching ratio is 4 times. The stretched fiber is extracted with water at 60°C, and then heat-set to obtain a Rapidly oxidized polyacrylonitrile precursors have a strength of 3.7cN / dtex and a degree of cyclization of 30%. The PAN precursor was raised to 240°C at 4°C / min, kept at constant temperature for 1.5h, and the cyclization reaction was basically completed.

Embodiment 2

[0028] Mix the dried polyacrylonitrile and 1-butyl-3-methylimidazolium chloride salt ionic liquid uniformly at a ratio of 1:1.8, add the mixture into the twin-screw and simultaneously feed air into the twin-screw for spinning, The spinning temperature was 180°C, and the winding speed thereof was 500 m / min. The spun spun silk is directly stretched by dry heat, the stretching temperature is 120°C, and the stretching ratio is 4 times. The stretched fiber is extracted with water at 60°C, and then heat-set to obtain a Rapidly oxidized polyacrylonitrile precursors have a strength of 4.22cN / dtex and a degree of cyclization of 25%. The PAN precursor is raised to 240°C at 4°C / min, and the temperature is kept constant for 1h, and the cyclization reaction is basically completed.

Embodiment 3

[0030] Mix the dried polyacrylonitrile and 1-methyl-3-ethylimidazolium chloride ionic liquid uniformly at a ratio of 1:1, add the mixture into the twin-screw and simultaneously feed air into the twin-screw for spinning , the spinning temperature is 220°C, and the winding speed is 600m / min. The spun spun silk is directly stretched by dry heat, the stretching temperature is 180°C, and the stretching ratio is 10 times. The stretched fiber is extracted with 80°C water, and then heat-set to obtain a Rapidly oxidized polyacrylonitrile precursors have a strength of 6.35cN / dtex and a degree of cyclization of 42%. The PAN precursor was raised to 240°C at 4°C / min, and the temperature was kept constant for 0.5h, and the cyclization reaction was basically completed.

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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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): D01F11/06D01F6/18
Inventor 余木火田银彩韩克清荣怀苹覃辉林严斌王丹
Owner DONGHUA UNIV
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