A kind of drawing method of polyacrylonitrile fiber

Abstract

The invention relates to a polyacrylonitrile fiber stretching method which comprises the following steps: extruding a polyacrylonitrile spinning solution, moving into a coagulation bath for forming via or not via an air layer, moving into a stretching bath through a guide roller, and then performing multi-stage stretching on polyacrylonitrile fiber in saturated steam, wherein the polyacrylonitrile fiber comprises 30-95 wt% of polyacrylonitrile, 3-40 wt% of solvent and the balance of water; the steam pressure P1 of the saturated steam for first-stage steam stretching is kept at 0.11-0.15+ / -0.01 MPa, and the steam pressure PN for final-stage steam stretching is kept at 0.40-0.43+ / -0.01 MPa; and the multi-stage stretching is 2-7 stages, and the total stretching ratio is 3.0-29.7. The polyacrylonitrile fiber stretching method improves the orientation degree and the mechanical strength of macromolecular chains in the fiber, reduces the solvent residue in the fiber and enhances the performance of the fiber.

Description

Technical field [0001] The invention relates to a stretching method of polyacrylonitrile fiber, belonging to the field of polyacrylonitrile fiber preparation. Background technique [0002] Polyacrylonitrile fiber (PAN) is a synthetic fiber with excellent performance and an important fiber raw material for textile and industrial use. The industrialized spinning process of polyacrylonitrile fiber includes wet method, dry method and dry spray wet method. In the process of wet spinning and dry jet wet spinning, coagulation forming in a coagulation bath, washing and stretching in a water bath, washing with a large amount of water, drying and heat setting and other important process steps, are used in the production of high-quality special-purpose polyacrylonitrile fiber. In the preparation process, it is often necessary to perform high-temperature steam stretching on the dried fiber to improve the regularity and mechanical properties of the fiber structure. [0003] The publication nu...

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Problems solved by technology

[0004] In the method disclosed in the above-mentioned method, one or more washing tanks are required for water washing stretching or spray washing, which requires a large amount of water to remove a small amount of solvent in the fiber, and produces a large amount of waste liquid containing spinning solvent, and after After multiple washings, the removal effect of the solvent in the fiber is limited, and there is still a small amount of solvent remaining, which affects the mechanical and thermal properties of the fiber, and then affects the quality of the fiber; and the use of atmospheric pressure water vapor to remove the solvent, the solvent removal effect is better than that of a large amount of water. The effect is good, but because it is removed in atmospheric pressure steam, no stretching is applied during the process to increase the removal efficiency, and there is still a small amount of solvent remaining in the fiber

[0005] The high-stretching of the PAN fiber of the carbon fiber precursor is realized in the steam stretching process section. Usually, the steam stretching needs to be carried out under a certain temperature and pressure. The existing steam stretching usually requires a steam pressure of 0.6 MPa or more. Therefore, It is required that the steam stretching device has higher sealing performance, and the patent of publication number CN101235568A discloses a steam pressure sealing device, and a high-temperature gas sealing chamber with the same pressure as that of the steam stretching chamber is used at both ends of the steam stretching chamber Connected to ensure the temperature and pressure in the water vapor stretching chamber to achieve the purpose of high-stretching polyacrylonitrile fibers. The utility model patent No. 02247164.2 uses a steam chamber outside the steam chamber to increase the steam temperature and pressure and The sealing of the device, these methods are to further modify the steam stretching device to improve the sealing of the stretching device. Although this improves the stretching effect to a certain extent, the workload and cost are high for the modification of the device. High temperature and high pressure resistance is required for equipment, and a large amount of energy is required to achieve high vapor pressure