Machine modification to solve color contamination problem in yarn printing machines
Dyeing of the yarn by the roller printing method involve staining problem. These problems result from contact of the yarns each other during winding of the yarn on the hank by the conventional winding technology. A new winding system was developed to overcome this problem. The new winding system established on conventional winding machine by modification of the machine and developing a new software.
While yarns of different colors overlap each other and cause yarn staining in the conventional winding technique, yarns of different colors are wound on the hank separately in this new technique, thus preventing staining. In other words, thanks to the new winding technique, the contact of different colored yarns wound on the hank is eliminated and the staining problem is eliminated.
- Introduction
Dyeing and printing methods have been used for centuries to color textile surfaces. The painting method is based on the principle of painting the surface with a dyestuff without a certain area limit. In the printing method, a limited coloring process is carried out in a determined area on the surface. In the textile industry, printing can be done as tops, yarn, fabric or ready-made garments. In this study, only printing method of hand knitting yarns will be explained [1-4].
Hand Knitting yarns are generally soft twisted, bulky and thick yarns that are produced from acrylic fiber [5]. These products are manufactured by running a sequential series of processes which are stretch tow breaking, carding, drawing, yarn cleaning, folding and twisting, yarn printing, fixation and balling. In general, applications performed as yarn printing are called space dyeing and yarn printing processes are mostly done with space dyeing applications [1-4]. Dyeing processes of this yarns can be done in different methods, one of this method is yarn printing dyeing. In this method, yarn can be dyed 6 different colors by using changeable pattern length by using printing machine as seen from Figure 1.
Figure 1: Yarn printing
Figure 2: Knitting fabric sample which produced from print dyeing yarn
Hand knitting yarns are produced from acrylic fibers so that basic dyestuff is used as a dyestuff. During dyeing process, print paste is transferred to the yarns by roller printing method and then drying-fixing processes is applied. After printing, the yarn is dried with a perforated system that delivers hot air and wound on the hanks. The fixation of the dyestuff is done with saturated steam [2-4]. After these operations, the colored yarn is transferred to the hank parts. In machines with 6 printing cylinders, 6 different colors can be applied onto the yarn so the yarn can be dyed in 6 different colors within yarn length.
After dyeing process, some dyestuff not reacted with fiber molecular structure or were hydrolyzed in the dye bath. As a result of this situation, the result of color fastness can be low, the migration of dyestuff can be high [6,7]. After dyeing with basic dyestuff, some unfixed dyestuff can stay on the fiber. So that reason it causes color contamination on the other yarn [8].
In case of this type of dyeing procedure there is no color contamination problem if color difference in short patterns. But it has been observed that there is color contamination in the yarns in case of color difference in long patterns. This problem can be seen especially sequence in dark & light color tones.
The mentioned problem appears as a major mistake on the fabric after knitting operation. (Figure 4) This problem causes customer dissatisfaction and losing market share. For the solution of this problem, different alternatives have been considered in the company like that production speed has been reduced to increase the fixation time, but these solutions increased the production cost and the problem could not be solved permanently.
Figure 3: Printing dyed yarn on the hank winder
Figure 4: Contamination of the white yarn by red dyestuff
- Materials and Methods
This staining problem continues to happen at different times even if lots of precaution has been taken. For solving this problem permanently, the modification of the print dye machine winding system has been decided according to literature review. Modification has been made in two ways, one of them is developing new software and the other of them is modification of the winding system of the machine. Winding system modification was based on the changing traverse driving and mechanic units. The conventional machine winding system was drive by the gear system through main motor. Because of that the stroke of the traverse was short and not to be controlled. The new drive system includes servo motor which provide longer stroke and control of the travers. The figure 5 is general view of the newly designed traverse mechanism on the back creel (Scale: 1:15).
Figure 5: The general view of the newly designed traverse mechanism on the back creel
- Results and Discussions
As seen in the figure 6 the new developed software involves control of the traverse driving units. By using this program, the travers unit of the winding system can be controlled result in winding different color yarn separately on the hank. As mentioned in Section II, the servo motor and other parts included in the travers mechanism are seen in detail in Figure 6. The travers mechanism which transferred the yarn to the hank mechanism on the machine, converted to computer-controlled system which cause automatically color changing detection. By using this type of winding mechanism each color has been transferred in different length and different area on the hank wheel (Figure 7). The detection can be made from machine setup and drive the motor which drive the yarn winding carriage.
Figure 6: The travers mechanism
Figure 7: The software program that controls traverse driving unit
By this way, staining of the yarns under temperature and pressure is prevented, because of not wrapping of different colors yarns on each other (Figure 8).
Figure 8: The separated view of yarns of different colors on the hank thanks to the modified machine
Figure 9: Knitting fabric from print dyeing yarn produced by modified machine setup
4. Conclusions
With the new system that has been developed, the problem of contamination in print machines threads produced in printing machines, especially in dark and light tone colors transitions, has been prevented. In this way, the machine capacity has been improved and the operation times in the subsequent drying and hank wrapping processes have been shortened by approximately 10%.
References
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[2] Şenol D. (2004). Space boyama teknolojisi.
[3] Rouette H.K. 1995. Space Dyeing, Lexikon Für Textileveredlung, Vol.1, no.3. p.2003-2012.
[4] http://www.superba.com/GB /products/syn_DL5.html
[5] Ormo Yün İplik San. ve Tic. A.Ş., Kalite Yönetim Sistemi-Süreçler/Tarama, Üretim, Boyahane.
[6] Lin L., Ramhan Z., Wen S., Navik R., Zhang P., Cai Y. (2016). Improvement of colour fastnes for deep blue shade of cotton fabric, 4th International Conference on Machinery, Materials and Computing Technology, China.
[7] Tekstil teknolojisi selülozu boyama, http://www.megep.meb.gov.tr/mte_program_modul/moduller_pdf/Sel%C3%BClozu%20Boyama%201.pdf/1, Accessed: 01.October.2019.
[8] Uddin M.G. and İslam M. 2015. Effects of Different Soaping and Fixing Agents on Washing Fastness of Reactive Dyed Cotton Fabric, Journal of Multidisciplinary Engineering Science and Technology, Vol.2, no.1. p.57-61.
