A method for preparing polyacrylonitrile carbon fiber precursors by dry jet wet spinning

Abstract

The invention relates to a method for preparing a polyacrylonitrile carbon fiber precursor. The method comprises the following steps of: copolymerizing acrylonitrile and copolymerization components in multicomponent solution so as to form polymer spinning stock solution which has a relatively uniform and controllable molecular structure, performing demonomerization on the spinning stock solution,defoaming, filtering, and preparing the polyacrylonitrile carbon fiber precursor by a dry-jet wet-spinning process. The key technology of the method is that: a gas storage box is arranged on a dry wet spinning pack, the gas storage box and the liquid level of coagulating bath fluid form a dry-jet wet-spinning air layer into a confined space, and ammonia is persistently aerated into the space to carry out gas-liquid reaction with spinning solution trickle in the air layer. The polyacrylonitrile precursor prepared by the method has regular sections and few defects, the density is not less than 1.187g/cm<3>, the density after carbonization is not less than 1.79g/cm<3>, the strength is not less than 5.1GPa, and the modulus of elasticity is 280 to 300GPa.

Description

Technical field [0001] The invention relates to a dry-wet spinning preparation process of polyacrylonitrile-based carbon fiber precursors, in particular to a special dry-stage atmosphere to improve the hydrophilicity of nascent filaments to improve the solidification process to obtain regular cross-sections and compact structures The method of uniform polyacrylonitrile carbon fiber precursor. Background technique [0002] Carbon fiber has the advantages of high specific strength, high specific modulus, high temperature resistance, creep resistance, and certain electrical conductivity. It has been widely used in various fields such as aerospace, transportation, medical equipment, sports, and new energy. [0003] High-quality polyacrylonitrile precursor is the prerequisite for preparing high-performance polyacrylonitrile carbon fiber. In the process of preparing polyacrylonitrile precursor, the coagulation process is a crucial step. Studies have shown that increasing the hydrophilic...

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Problems solved by technology

[0004] Chinese patent 200910234654.X discloses a method for preparing high-strength polyacrylonitrile-based precursors for carbon fibers, including preparing a spinning stock solution with acrylonitrile and itaconic acid as comonomers, degassing the stock solution after single-filtering, spinning and After forming in DMSO coagulation bath, hot water drawing, adding silicone oil agent and heat densification treatment, and then steam drawing and setting, the disadvantage is that the density and cross section of the prepared raw silk are difficult to meet the requirements

[0005] Chinese patents 02130022.4 and 02130023.2 mention that polyacrylonitrile homopolymers are first synthesized, and then ammonia gas is passed into the polymerization liquid to control temperature and pH value, so that some functional groups can be converted into carboxyl and amide groups, thereby improving the affinity of polyacrylonitrile. Aqueous and spinnable, but due to the difficult diffusion of ammonia gas in the high-viscosity polyacrylonitrile solution, the reaction is not easy to control, and the operability and reproducibility of this method are poor

[0007] Chinese patent 20081131152.7 mentions that a certain amount of basic compound is added in the copolymerization system, through the reaction of the basic compound with the relevant components in the copolymerization system, the association between the components in the system is promoted, and the polymer When the spinning solution is coagulated, it can effectively improve the uniformity of coagulation and diffusion between the sheath and core of the solution, but the added compound remains in the polymer, which makes the anti-aging performance of the prepared product poor

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