The defoaming method of polyacrylonitrile stock solution

Abstract

The invention relates to a defoaming method for preparing a polyacrylonitrile stock solution, and aims at solving the problems that a stock solution in the prior art is not uniform, and an upper layer easily generates gel, or is even dried and hardened. According to the technical scheme, the defoaming method for preparing the polyacrylonitrile stock solution comprises the following steps: (a) starting a heating device, heating a defoaming kettle, starting a vacuum pump, vacuumizing the defoaming kettle, slowly conveying the polyacrylonitrile stock solution to the defoaming kettle from a demonomerisation kettle while vacuumizing, closing the vacuum pump after the polyacrylonitrile stock solution completely enters the defoaming kettle, introducing gas to the defoaming kettle, pressurizing and defoaming; (b) after pressurizing and defoaming are finished, starting the vacuum pump, vacuumizing the defoaming kettle, defoaming in vacuum, so as to obtain the final polyacrylonitrile stock solution, and the problems are relatively well solved; the defoaming method can be applied to industrial production of a carbon fiber precursor.

Description

technical field [0001] The invention relates to a method for defoaming polyacrylonitrile stock solution. Background technique [0002] Carbon fiber can be obtained by carbonization of polyacrylonitrile fiber, pitch fiber, viscose or phenolic fiber, among which polyacrylonitrile (PAN)-based carbon fiber is the most widely used, the largest amount, the fastest growing, and occupies an absolute position in carbon fiber production. Advantage. In the preparation process of PAN-based carbon fiber precursor, like most other man-made fibers, the removal of air bubbles in the spinning solution is involved. [0003] The solution will generate bubbles during polymerization or transportation; on the other hand, since the polymerization uses azo compounds as initiators, the nitrogen generated during decomposition is also mixed in the original solution to form bubbles. The polyacrylonitrile stock solution used for carbon fiber spinning has a relatively high viscosity, and these bubbles ...

AI Technical Summary

Problems solved by technology

[0007] The technical problem to be solved by the present invention is that high temperature and high vacuum degassing in the prior art tends to make the stock solution inhomogeneous, produce gel or even dry out, and provide a new degassing method for polyacrylonitrile stock solution