Prepn. of polyacrylonitrile-base high-performance raw carbon fiber

Abstract

The present invention relates to the preparation of high-performance polyacrylonitrile-based carbon fiber. Acrylonitrile, itaconic acid and methyl methacrylate in a certain weight proportion are reacted to obtain spinning dope, and the spinning dope is made into greign fiber of high-performance carbon fiber through filtering, solidification, water washing, drafting in hot water, oiling, drying and densifying, re-oiling, drying and densifying for the second time, steam drafting and drying setting. The present invention has the advantages of high drafting rate, homogeneous fibre structure, and small mechanical performance variation coefficient.

Description

[0001] Field: [0002] The invention belongs to a method for preparing fiber precursors, in particular to a method for preparing polyacrylonitrile-based high-performance carbon fiber precursors. Background technique: [0003] In the usual polyacrylonitrile raw silk spinning process, a filter cloth of about 400 meshes and ordinary absorbent cotton are generally used to filter the spinning stock solution. Although this filtering method can filter out the impurity particles in the stock solution, it is not suitable for gels below 5 μm The particles are helpless, and these gel particles, if not removed, will cause tiny defects in the precursor, which will affect the performance of the precursor. [0004] The coagulation bath process is the most important process step that affects the properties of the precursor. Among them, the temperature and concentration of the coagulation bath are two important process parameters. Increasing the concentration of the coagulation bath and lower...

AI Technical Summary

Problems solved by technology

Among them, the temperature and concentration of the coagulation bath are two important process parameters. Increasing the concentration of the coagulation bath and lowering the temperature of the coagulation bath are conducive to slowing down the double diffusion process of the primary filaments in the coagulation bath to obtain densified coagulation filaments, which is beneficial to The acquisition of high-performance raw silk. Increasing the concentration of the coagulation bath will inevitably lead to a higher solvent content in the coagulated silk, which increases the concentration difference between the coagulated silk and the washing tank, which will easily cause the skin-core structure of the raw silk and destroy the original silk. Homogenization degree of silk

[0005] The usual polyacrylonitrile raw silk spinning process generally adopts a 1-2 stage boiling water drawing process, and the primary filaments are drawn at a high rate of 3 to 4 times in boiling water. However, for high molecular weight and high viscosity spinning dope , it is difficult to carry out large-scale drafting

[0006] The usual polyacrylonitrile raw silk spinning process generally uses a hot air drying oven or an infrared hot plate to dry and densify the fiber after drawing. However, such a process is likely to cause uneven heating of the filaments, thereby affecting the microstructure of the raw silk. Uniformity, which in turn leads to an increase in the coefficient of variation of the mechanical properties of the precursor