Method for preparing high-strength carbon fiber

A carbon fiber and high-strength technology, which is applied in the field of high-strength PAN-based carbon fibers and the preparation of high-strength carbon fibers, can solve the problems of introducing defects in molecular chains, increasing production costs, and reducing mechanical properties of carbon fibers, and achieves good guiding significance. Effect

Inactive Publication Date: 2011-08-17
BEIJING UNIV OF CHEM TECH
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

In the later stage of pre-oxidation and carbonization treatment, it is easy to introduce defects in the molecular chain, which will cause the reduction of the mechanical properties of carbon fibers.
Therefore, the equal residence time in each temperature zone may not be conducive to the transformation of PAN molecular chain structure and the progress of thermochemical reactions.
In addition, the residence time in each temperature zone is approximately equal, and it is possible to increase some additional residence time, causing an increase in pre-oxidation time, which in turn causes an increase in production costs, so the residence time of fibers in each temperature zone should be different

Method used

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  • Method for preparing high-strength carbon fiber
  • Method for preparing high-strength carbon fiber
  • Method for preparing high-strength carbon fiber

Examples

Experimental program
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Effect test

Embodiment 1

[0014] Select the commercially available British Courtaulds company of wet spinning to produce, the PAN copolymer fiber (its filament tow is 12K that contains more than 90% acrylonitrile monomer component) is: acrylonitrile (AN): Methyl acrylate (MA): itaconic acid (IA) = 92.8: 6.0: 1.2, equilibrium moisture content 0.67%), in air medium, using 210 ° C, 230 ° C, 250 ° C, 270 ° C four-stage pre-oxidation furnace Treatment, residence time is respectively: 15min, 17min, 6min, 15min, totally 53min, draft ratio is 10%, obtains pre-oxidized fiber, the volume density of the pre-oxidized fiber after heat treatment in 250 ℃ temperature zone is shown in Table 2, pre-oxidized Under the protection of nitrogen, the fiber is subjected to low-temperature carbonization at 350°C, 480°C, 580°C, and 680°C. The residence time in each temperature zone is 1min, a total of 4min. Apply +4% draft ratio; apply at 1250°C -3% draw ratio, carbonization at high temperature for 2 minutes, to obtain carbon f...

Embodiment 2

[0016] The PAN copolymer fiber used and other operation steps are all the same as example 1. Among them, the pre-oxidation gradient temperature is 210°C, 230°C, 250°C, 270°C four-stage pre-oxidation furnace treatment, the residence time is 15min, 17min, 9min, 15min, a total of 56min, and the draft ratio is 10%. fiber. Under the protection of nitrogen, the pre-oxidized fiber was subjected to low-temperature carbonization at 350°C, 480°C, 580°C, and 680°C. The residence time in each temperature zone was 0.8min, a total of 3.6min, and a +5% draft ratio was applied; A draft ratio of -2% was applied at a temperature of 1300°C, and carbonized at a high temperature for 2.5 minutes to obtain carbon fibers. The results are shown in Table 1 and Table 2.

Embodiment 3

[0018] The PAN copolymer fiber used and other operation steps are all the same as example 1. Among them, the pre-oxidation gradient temperature is 210°C, 230°C, 250°C, and 270°C for four-stage pre-oxidation furnace treatment, the residence time is 15min, 17min, 12min, and 15min respectively, a total of 59min, and the draft ratio is 10%. fiber. Under the protection of nitrogen, the pre-oxidized fiber was carbonized at a low temperature at 350°C, 480°C, 580°C, and 680°C. The residence time in each temperature zone was 0.7min, a total of 2.8min, and a +6% draft ratio was applied; Apply a draft ratio of -3% at a temperature of 1350°C, and carbonize at a high temperature for 3 minutes to obtain carbon fibers. The results are shown in Table 1 and Table 2.

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Abstract

The invention discloses a method for preparing a high-strength carbon fiber, belonging to the technical field of the carbon fiber. The method comprises the following steps of: pre-oxidizing a polyacrylonitrile (PAN) copolymer fiber under air atmosphere at the temperature of between 200 DEG C and 280 DEG C; performing heat treatment for 50 to 70 minutes in a four-section to seven-section gradient heating mode; keeping at a temperature zone with heat treatment temperature of 250 DEG C for 9+/-3 minutes; and carbonizing the pre-oxidized fiber under conventional carbonizing conditions, namely carbonizing the fiber under protection of a nitrogen gas at the draw ratio of -4 to +8 percent and at the low temperature of between 300 DEG C and 900 DEG C for 3+/-1.5 minutes, and carbonizing the fiber at the high temperature of between 1,200 DEG C and 1,600 DEG C and at the draw ratio of -4 to +1 percent for 2+/-1 minutes. The carbon fiber prepared by the method has a perfect structure and excellent mechanical property. The tensile strength of the obtained carbon fiber reaches over 3.8GPa.

Description

technical field [0001] The invention relates to a method for preparing high-strength carbon fibers, which can produce high-strength PAN-based carbon fibers with a tensile strength above 3.8 GPa, and belongs to the technical field of carbon fibers. Background technique: [0002] The time spent in the pre-oxidation process accounts for more than 80% of the carbon fiber preparation time. How to significantly reduce the time spent in the pre-oxidation process while improving or maintaining the mechanical properties of carbon fibers is crucial to reducing the cost of carbon fiber preparation and improving the mechanical properties of carbon fibers. important. At present, for the research on the pre-oxidation time of PAN fiber, the method of multi-stage gradient temperature rise is mostly used, and the residence time in each temperature zone is approximately equal. However, due to the complexity of the PAN fiber structure, there are certain differences in its physical structure t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D01F9/22
Inventor 刘杰张月义连峰马兆昆梁节英
Owner BEIJING UNIV OF CHEM TECH
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