Polyacrylonitrile copolymer spinning solution and preparation method thereof

Abstract

The invention relates to a polyacrylonitrile copolymer spinning solution and a preparation method thereof. In the invention, copolymerization reaction is performed on acrylonitrile in a tubular reactor containing a static mixer component; the tubular reactor, which contains the static mixer component and has the characteristics of mass transfer, efficient heat transfer, continuous and stable reaction and no mechanical stirring, is adopted to prepare the polyacrylonitrile copolymer spinning solution with high molecular weight and narrow molecular weight distribution. The polyacrylonitrile copolymer spinning solution is obtained after copolymerization reaction is performed on reaction liquid composed of monomers, a radical initiator and a solvent, wherein the percent concentration by weight of the monomers in the reaction liquid is 15% to 20%; the weight of the radical initiator is 0.4% to 1% of that of the monomers; the solvent is in balancing amount; the monomers are an acrylonitrile monomer and a comonomer. The dynamic viscosity of the polyacrylonitrile copolymer spinning solution provided by the invention is 200 to 800 Pa.S, and the molecular weight distribution is 1.5 to 2.6.

Description

technical field [0001] The invention belongs to the field of polyacrylonitrile preparation, in particular to a polyacrylonitrile copolymer spinning solution with uniform viscosity and narrow molecular weight distribution and a rapid and stable preparation method thereof. Background technique [0002] Carbon fiber has the characteristics of high specific strength, high specific modulus, heat resistance, corrosion resistance, fatigue resistance, and creep resistance. It is a high-performance fiber material and has been widely used in aerospace, national defense construction, sports and leisure products, and medical equipment. and construction industries. Polyacrylonitrile-based carbon fiber has outstanding mechanical properties and is a hot spot in carbon fiber research and industrialization in recent years. The key to restricting the development of polyacrylonitrile-based carbon fibers is the quality of polyacrylonitrile precursors, and to obtain high-quality polyacrylonitri...

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Problems solved by technology

[0003] At present, polyacrylonitrile for carbon fiber in China is mostly prepared by solution polymerization with azo initiators, and batch polymerization is adopted. Due to the intense heat release of acrylonitrile polymerization and the high viscosity of the system in the later stage of polymerization, mass transfer and The heat is difficult and the reaction is difficult to control, so that the molecular weight distribution of polyacrylonitrile is broadened and the gel content is increased, which significantly affects the improvement of subsequent fiber properties; first of all, from the perspective of polymer production technology, the main reaction of batch polymerization is non- In the steady state process, the exotherm is concentrated and the viscosity changes greatly. It is difficult to provide a reasonable stirring form that takes into account the low viscosity and fast exotherm at the beginning of the polymerization and the high viscosity and slow exotherm at the later stage of the polymerization. As a result, chain transfer to the solvent is prone to occur during polymerization. reaction, which is not conducive to the preparation of high molecular weight polymers; secondly, the gel effect is prone to occur in the stage of high conversion rate and high viscosity, resulting in a large change in the molecular weight of the polymerization stock solution and a widening of the distribution; moreover, the viscosity is extremely high in the late stage of polymerization, which causes the material in the kettle to stir It is difficult to mix, it is difficult to remove the heat of the material in the kettle, and it is prone to explosion polymerization, so the production of the polymerization stock solution is difficult to carry out stably

The precursors spun from this copolymer have poor stability in terms of microscopic physical structure and chemical reactivity, which adversely affects the stable production and performance of carbon fibers

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