Method for preparing carbon fiber precursor by employing sodium thiocyanate through dry and wet spinning process

Abstract

The invention discloses a method for preparing carbon fiber precursor by employing sodium thiocyanate through a dry and wet spinning process. The method comprises the following steps: taking a sodium sulfocyanate aqueous solution as a solvent for polymerization to obtain a polymerization stock solution, passing the polymerization stock solution through a first demonomerization tower for removing an unreacted monomer in the polymerization stock solution, then preheating the material to the temperature of 75-85 DEG C and introducing the material into a second demonomerization tower, and wherein content of a residual monomer is controlled at less than or equal to 0.1%, preheating the demonomerized polymerization stock solution to the temperature of 70-95 DEG C, defoaming the polymerization stock solution under a pressure reduction state and then dehydrating, then performing multistage cyclic preheating, defoaming and dehydrating to obtain the high-density (high solid content) spinning stock solution which satisfies the dry and wet spinning requirements, and spinning to obtain the carbon fiber precursor. The method is simple, the obtained carbon fiber precursor has good wire drawing capability, nozzle stretching is stable, breakage rate is little, precursor dispersion is little, and intensity is high.

Description

Technical field [0001] The invention relates to a method for preparing a carbon fiber precursor by a polyacrylonitrile-based carbon fiber dry-wet spinning process, in particular to a method for preparing a polyacrylonitrile-based carbon fiber precursor by adopting a sodium thiocyanate aqueous solution dry-wet spinning process. Background technique [0002] The most commonly used spinning method of PAN precursor is wet spinning. With the continuous expansion of the application field of carbon fiber, the production cost and performance requirements of carbon fiber are getting higher and higher. The dry and wet raw yarn has less surface and internal defects, high density, easy to control cross section, and has a high-power spinneret. Stretching and high spinning speed (5-10 times that of wet spinning) are very beneficial to high-strength carbon fibers and greatly reducing production costs. It is the current development direction of carbon fiber precursor production. [0003] Dry-wet ...

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Problems solved by technology

However, the solubility of sodium thiocyanate aqueous solution is lower than that of organic solvents such as DMSO, DMF, and DMAc, and the viscosity of the stock solution is low, so it has a tendency to separate out gel at a lower composition content, and the concentration (solid content) of the spinning stock solution is generally between Between 12wt% and 13wt%, it is difficult to meet the requirements of high concentration and high viscosity of dry and wet spinning dope

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