Abstract:

Objective In modern textile industry, the reduction of yarn hairiness has become more critical than improving yarn strength and abrasion resistance in the sizing process. In order to further reduce warp hairiness, this paper reports a method for enhancing the hairiness reduction during the drying process in warp sizing based on the analysis of hairiness attaching mechanism.
Method A laboratory scale XSY617-700 sizing machine was used for research. The sizing guide roller between the pre-drying drum and the combined drying drum was transformed into an actively rotating hairiness attaching roller to build a hairiness attaching device. According to the rule that the adhesion force of the size liquid carried by the yarn changes with the drying process, the effect of scraping action on the surface of the yarn by the hairiness attaching roller was studied. The values for two system parameters, the liquid content of the yarn when it is scraped by the roller and the friction length applied by the roller were optimized to achieve the beset hairiness reduction effect.
Results Based on the above device and method and under the same scraping action, the moisture regain of the yarn was controlled from 40% to 10% and the hairiness performance index was measured when adjusting the temperature of the pre-drying drum. The number of unwanted hairiness showed a trend of increasing first and decreasing afterwards (Fig. 3). The possible reason for this phenomenon was that after pre-drying, the moisture regain of sized yarn was reduced and the concentration of liquor in the yarn was increased, which improved the adhesion of the hairs to the yarn body. While after the moisture regain of sized yarn was reduced to a certain level, the yarn and the hairs was drying out thus the adhesion of them was reduced, more hairs could not be adhered to the yarn surface. It showed that 20% moisture regain of sized yarn was more beneficial in reducing harmful hairiness in the proposed system. The friction length was a comprehensive representation of the operating parameters of the hairiness attaching device, and it was used as a control variable influencing the hairiness reduction effect. When the moisture regain of sized yarn was set as 20% as optimized above, and the friction length was controlled to vary the extent of the applied scraping action. As the friction length increased the scraping action increases and the number of harmful hairiness showed a decrease followed by an increase (Fig. 4). The possible reasons were considered as follows. Firstly, a higher friction length indicated a longer actuation duration of the adhesion effect leading to more hairs being adhered, which would approach a maximum as the friction length increases, while a higher friction length also indicated a higher possibility of adhered hairs to be scraped from the yarn surface. Under the combined effect of them, the unwanted hairiness decreased as the friction length increased at first and increases after the friction length reached a certain point. Finally, under the experimental conditions of this research, when the proposed hairiness attaching device was established and applied, a friction length controlled around 81.6 mm would be more beneficial to the harmful hairiness reduction.
Conclusion With the optimal combination of the parameters and under the experimental conditions in this research, the proposed hairiness attaching device has been proved to be able to reduce the unwanted hairiness by 36.3%. The best reduction of hairiness is achieved when the system parameters are set to 20% moisture regain and 81.6 mm of friction length of the roller attachment effect. The hairiness attaching method and the parameter optimization method proposed in this research can be applied to the production process, considering analysis of the variation of moisture regain of yarn on the target sizing machine, selection of appropriate device forms, device installation position, and the adoption of process parameters for achieve convenient, efficient and stable hairiness attaching.

Key words: sizing process, unwanted hairiness, hairiness attaching roller, moisture regain of sized yarn, friction length, drying