Preparation method of polyacrylonitrile resin with evenly-distributed copolymerization sequence

Abstract

The invention relates to a preparation method of polyacrylonitrile resin with an evenly-distributed copolymerization sequence. The preparation method comprises the following steps: carrying out suspension polymerization among acrylonitrile, a second copolymer monomer with an improved drawing performance, and a densified and stabilized third copolymer monomer in a water medium for 1 to 4 hours at a reaction temperature of 45 to 58 DEG C in the presence of an initiator comprising water-soluble oxidant and reductant; using a sodium hydroxide solution as a terminator to stop the reactions, removing the unreacted monomers after the reactions, and finally carrying out suction filtering in vacuum under water-washing. The polyacrylonitrile resin, which is prepared through a water phase suspension polymerization technology, is taken as the spinning raw material. During the polymerization process, third copolymer monomers are added through a special way to make the third copolymer monomers be evenly polymerized to a PAN macromolecular chain in a reactor so as to obtain polyacrylonitrile resin with a third copolymer monomer even copolymerization sequence length and sequence distribution.

Description

technical field [0001] The invention relates to a preparation method of polyacrylonitrile resin with uniform distribution of copolymerization sequence, in particular to a preparation method of polyacrylonitrile resin with uniform distribution of copolymerization sequence by aqueous phase suspension polymerization process. Background technique [0002] The production of polyacrylonitrile-based carbon fiber involves multiple complex processes, including polymerization, spinning, pre-oxidation and carbonization, etc. It is a highly related system engineering. Therefore, to achieve stable production and performance improvement, the process of each process should be considered as a whole Conditions are very necessary. The basis for determining the process conditions is the relationship between the molecular chain structure of polyacrylonitrile as a precursor and the structure and performance of carbon fibers. The molecular structure of polyacrylonitrile includes molecular weight...

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Problems solved by technology

In the prior art, there is an adjustment by increasing the amount of a comonomer with low reactivity, but this adjustment method only adjusts the length of the copolymerization sequence, not the uniformity of its sequence distribution

[0005] In conventional reactors for preparing polyacrylonitrile resins, the height of the reactor is usually much larger than the diameter, and multi-layer stirring paddles are usually used. Under the action, multiple flow field boundary partitions are generated, and the materials in the various sectors are mixed well, but the mixing effect of the materials in the various sectors is not good, and the effect of full mixing in the reactor cannot be achieved. Even if the full mixing effect can be achieved, due to factors such as material viscosity , the diffusion rate of comonomer is also much lower than the polymerization reaction rate, so that the reaction monomer with high reactivity rate is consumed quickly, and the reaction monomer with low reactivity rate is consumed slowly, so that the generated polymer sequence distribution is relatively small. Poor, unable to meet the requirements of oxidation and carbonization of raw silk

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