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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 reduced mechanical properties of carbon fiber, prolonging the pre-oxidation time, and aggravating the skin-core structure, so as to reduce the cost of carbon fiber and improve the pre-oxidation process. Oxidation rate, effect of improving structural compactness

Inactive Publication Date: 2011-11-23
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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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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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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