Industrialized polyimide fiber drafting method

Abstract

Disclosed is an industrialized polyimide fiber drafting method. The method includes that a certain deniers of polyimide yarn sheets with uniform tension are placed in a four-part type hotbox environment and clamped by a rubber roller, under a certain feeding speed, the yarn sheets achieve a certain multiple drafting through a speed difference between a front drafting machine and a rear drafting machine, and the four-part type hotbox is a combination of a prehearing section hotbox, a superheated steam humidifying section hotbox, a high temperature drafting hotbox and a setting hotbox. During the process of the fiber treatment, the temperature changing gradient is reasonable, the impact thermal load which is stressed on the fibers is small, and the probability that the yarn sheets generate broken filaments is remarkably reduced. The fibers are subjected to superheated steam humidifying treatment before the high temperature drafting, the static electricity in the yarn sheets is eliminated, the drafting force of the same number of fibers is reduced by 25%, the draft multiple is increased by 30%, and the strength of the fibers is increased 40%. After the polyimide fibers are subjected to the drafting and high temperature setting, the internal stress of the polyimide fibers is eliminated, the stability of the fiber structure is improved, and the shrinking rate of the polyimide fibers is maintained about 2%.

Description

technical field [0001] The invention relates to a polyimide fiber production technology, in particular to an industrial polyimide fiber drawing method. Background technique [0002] Polyimide fiber is a new type of high-performance fiber. Because it has many superior properties such as high strength, high modulus, high temperature resistance, radiation resistance, and chemical corrosion resistance, its research and development and production have received more and more attention recently. Much attention. Among them, the polyimide precursor fiber is prepared by using the polyamic acid solution as the spinning stock solution, and the polyimide fiber is obtained after cyclization and then drawn, and the processing is relatively convenient. Therefore, this method for preparing the polyimide fiber It has the potential of industrial production. [0003] After the polyimide fiber is cyclized, in order to obtain better strength, modulus and other properties, the degree of orientat...

AI Technical Summary

Problems solved by technology

Since the filaments enter the high-temperature environment at a certain speed, the large change in temperature will cause severe impact thermal load on the fibers, causing damage, thereby increasing the probability of the filaments producing fuzz

In the high-temperature drawing process, since the softening point of polyimide fiber is relatively high, reaching 500°C~700°C, the fiber needs to reach the softening point temperature for smooth drawing. It is easy to form fiber orientation, but the molecular chain cracking speed of polyimide fiber is accelerated under high temperature environment, which will have an adverse effect on the further improvement of fiber performance

After the polyimide fiber drawing process is completed, although its supramolecular structure has been basically formed, because some molecular segments are in a relaxed state, while others are in a tense state, there is uneven internal stress inside the fiber. , the crystalline structure in the fiber also has many defects. If the polyimide fiber directly enters the air at room temperature for the next crimping (short fiber) or winding (long fiber) process, it is not conducive to the formation of good mechanical and mechanical properties of the fiber. Performance, and can not meet the uniformity requirements for fiber-to-fiber performance in the application field

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