Suleiman Ndaro Mbwana, *Xiang-yu Jin, Optimum Water Jets Inclination Angle Ting Chen, Chongwen Yu for Better Tensile Strength in Hydroentanglement Process Department of Textile Engineering, Abstract An experimental set up was developed to evaluate the role of the water jet inclination *Department of Nonwoven, angle during the hydroentanglement process. Hydroentangled bicomponent nonwoven fab- Donghua University, rics were made using the inclined water jet apparatus designed. The effects of water jet Shanghai, 201620. P. R. China inclination angles are discussed and evaluation was made on the basis of the fabric tensile E-mail: [email protected] strength. The experimental results revealed that the use of inclined water jets increases the fabric’s tensile strength. An inclination angle of 10 degrees was the optimum, showing higher tensile strength for all nonwoven fabrics tested. These results confirmed that with an optimum water jet inclination angle in the hydroentanglement process, the fabric’s tensile strength can be improved. Key words: hydroentanglement, inclined water jets, optimum inclination angle, splittable bicomponent fabrics. pressure and specific energy to be con- washing, resulting in less fabric uniform- sidered for obtaining the maximum ten- ity. In their work the water jet pressure sile strength of fabrics. All of those stud- ranged from 40 - 1800 psi, and angle jets ies used perpendicular water jets. In the of 0 - 30 degrees and a jet density of 16 case of diverging water jets, experiments jets/cm were used. The fibre type used in were conducted by Bunting of DuPont this study was mainly 100% polyester. in 1964, as well as Zolin and Sternlieb However, after careful review of the lit- [18 - 20]. Bunting [21] set the manifold erature, there appears to be nothing about oblique to the linear direction of the the use of inclined water jets for splitta- woven cloth, but his method was never ble bicomponent fibres, hence research is commercialised since it was totally im- needed to form a deep understanding of practical and costly. Zolin [20] replaced the effect of inclined water jets on such Bunting’s oblique strip with a multivane fibres. Optimisation of the hydroentan- jet strip, each vane being discontinuous glement process leads to low energy and from the adjoining vane and consisting low water consumption during it; as a re- n Introduction of 3 or more holes per vane. From their sult, the running cost can be reduced. In Each nonwoven manufacturing system work they concluded that diverging wa- order to enhance the hydroentanglement involves the following: fibre/raw mate- ter jets can improve the performance of process, it is good practice to increase the rial selection, web formation, web con- woven fabrics. fibre bonding points. By doing this, an in- solidation, as well as web finishing and crease in the tensile strength is expected. converting. It has been reported that the Their methods were used for woven fab- To attain this goal, the use of inclined wa- technologies expected to gain more im- rics, but they were very complicated and ter jets was considered as a possible solu- portance are spun bonding, melt blow- costly since they referred to the change in tion due to their long path distance within ing, and hydroentanglement [1]. No mat- the manifold setting and did not specify the fibre web. In this paper we investi- ter how hydroentanglement systems may the angles used. Webster and Longmire gate the use of inclined water jets using vary from one manufacturer to another, [22] studied the vortex dynamics of jets different inclination angles. We evaluate the entanglement of fibre web requires from inclined nozzles and found that the changes in the tensile strength of nonwo- the following: a web supporting sub- radial spreading of jets increased with the ven fabrics and make a comparison to strate, water jet nozzles, water extraction, nozzle’s inclined angle; they concluded find out the optimum inclination angle water circulation and filtration [1 - 5]. In that as the inclination angle increased, the for obtaining maximum tensile strength. this study, a hydroentanglement unit was coherent structure rapidly broke down. designed to provide inclined water jets. n Experimental Recently, Oathout, J. M. et al [23] used The study of hydroentanglement units angled water jets to study the anisotropic Materials has been ongoing for many years, and nature of nonwoven fabrics. From their The island in sea bicomponent fibre, many researchers have shown that noz- study they concluded that when using 70%PET/30%COPET of 4 dtex lin- zle parameters and their configurations angled jets, the isotropy of hydroentan- ear density with 37 PET islands, and play a great role in the hydroentangle- gled fabrics was improved. Furthermore, 70%PA6/30%PET pie segment fibre of ment process [6 - 11]. However, other re- they reported that relatively low water jet 2.77 dtex linear density with 8 segments searchers[12 - 17] have studied the effect pressures were sufficient to achieve low were used in this study. Carded webs of of specific energy and jet pressure on the strength ratios compared to higher water 100 grams per square meter (gsm) for tensile strength of hydroentangled fabrics jet pressures ,which can achieve good each fibre type were produced using a and concluded that there is an optimum strength ratios but tended to cause jet conventional sampling carding machine. 82 Mbwana N. S., Jin X., Ting C., Yu C.; Optimum Water Jets Inclination Angle for Better Tensile Strength in Hydroentanglement Process. FIBRES & TEXTILES in Eastern Europe 2009, Vol. 17, No. 4 (75) pp. 82-86. The fibre length for all fibres was 51mm and each sample of carded web was cut Manifold into small pieces of 55 mm (width) by 175 mm (length). Five samples were ob- α =-10, -20 degree α =10, 20 degree tained corresponding to machine direc- Inclined water jets α α tions and crosswise directions, respec- Fiber web tively, all of which were marked to avoid mixing them. This allowed for greater ac- Inclination on left side Inclination on right side curacy in the processing of carded webs Vertical jets (α =0 degree) using small jet plates during hydroentan- glement. Figure 1. Inclination modes of water jets. Note: The fabric flow was directed in the front Preparation of or back with respect to the manifold and water jets perpendicular or angled from the perpendicular with respect to the fibre webs. hydroentangled samples The inclined water jet apparatus designed lengthwise and in a crosswise direction ues of their tensile strength at break were was used for the preparation of hydroen- (CD) width wise. Figure 2 shows a flow recorded. tangled nonwoven fabrics. The -20, -10, 0, 10, and 20 degrees of inclination of diagram of the process, and Figure 3 is an example of a jet plate in the small nozzle orifices on the jet plates (see Fig- n Results and discussions ure 1) and pressure levels of 3, 5, 7 and manifold of the inclined nozzle orifice at 10 bars were used to process the fabrics. an angle of 10 degrees used in this study. The tensile strengths at break of hydroen- Figure 1 clearly shows the meaning of tangled fabrics tested in accordance with the negative sign (-) as an inclination on The preliminary stage of this work was their processing variables are given in the left side of the web. done in a laboratory, from which it was Tables 1 & 2. derived that the processing variables, Two passes for each side of the fibre such as the water jet pressure, jet density, Trends in tensile strength webs were used during hydroentangle- nozzle orifice diameter are much differ- depending on the inclination ment, and the standoff distance between ent from the ones usually used in indus- angle of the water jet the nozzle orifice and fibre web was trial/commercial hydroentangling units. fixed at 20 mm. Other processing vari- The Figure 4 shows the trend in tensile ables were a jet density of 3 jets/cm, a Measurements strength depending on inclination angles. The curves in Figure 4 clearly show that nozzle orifice diameter of 0.3 mm and The preparation of all samples and tests web velocity of 0.72 m/min. The water the tensile strength at break increased up were carried out according to ASTM D in the pressure water tank was driven to the maximum value and then started 5035-95 (strip method) [24]. The tensile by air pressure from the air compressor to decrease. Figure 4 confirmed the opti- strength of hydroentangled non-woven downwards through the hydraulic hose mum inclination angle of 10 and -10 de- fabrics was measured using a Universal pipe, and eventually the water jets were grees as the best for providing higher ten- forced through the orifices, striking the Material Tensile Testing Machine (AGS- sile strength at constant pressure levels, fibre web fixed on the screen mesh. Since 500ND) at a constant rate of 250 mm/ followed by -20 and 20 degrees as their the jet plate was small, the shifting of min and gauge length of 100 mm. The tensile strength was higher than that of the fibre web along its width was carried dimensions of the samples was 50 mm perpendicular water jets. As can be seen on to cover a small area of the carded fi- by 170 mm in the machine (MD) and from Tables 1 & 2, other values of tensile bre webs until the sample was totally crosswise directions (CD). Five samples strength at the different pressure levels of hydroentangled.Webs in the machine were tested in the machine direction and 3.5, and 7 bars show the same trend as direction (MD) were hydroentangled crosswise direction , and the average val- that for 10 bars, as shown in Figure 4.