Patent Publication Number: US-2019186056-A1

Title: Multinucleus yarn with improved fibre distribution and terry fabric produced from the yarn

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to manufacture of yarns, and more particularly, the present invention relates to making yarns with improved distribution of packing density resulting in high softness, bulkiness and sustainable yarn geometry with enhanced strength and less hairiness, and a terry fabric produced from the said yarn with sustainable high bulk and improved appearance after repeated usage. 
     BACKGROUND OF THE INVENTION 
     Conventionally, terry towels which include loop structures tend to reduce retention of loop structure after repeated washing. Further, there have been many efforts to improve softness, for instance, by adding pores in the yarn or by reducing twist factor in the yarn. It has been observed that these methods result in compromised bulk and bulk retention of the end-product. Quality of yarn has a profound influence on the quality of a resultant fabric that is produced from the yarn. These fabrics are generally used for making various products such as towels, bathrobes, terry fabric for bed sheets etc. A good quality yarn is therefore desirable such that the end-product is of a quality and standard that appeals to the end-user and affords a high-end experience for use of the product. Various physical, structural and mechanical properties contribute to the quality of yarn. A number of factors have an impact on these properties and packing density is one such factor which affects the yarn behaviour. Packing density expresses the degree of arrangements of fibres in the yarn structure. Packing density is generally calculated by the ratio of total area of fibres to the cross-sectional area of the yarn. Various yarn characteristics such as yarn diameter, yarn compactness, yarn contraction, yarn porosity and volume are directly affected by packing density of yarn. 
     Spinning technologies used for spinning fibres in the manufacture of yarns has a vital role to play in the arrangement of fibres and in turn the packing density. For instance, in ring spinning processes, a web of fibres viz. roving is drafted and twisted by a ring and traveller arrangement. Twisting of fibres causes the fibres to be longitudinally strained and the fibres compete to reach a position of minimum strain at the centre (nucleus) or axis of the yarn. The fibres therefore tend to migrate towards the nucleus of the yarn. As a result of fibre migration towards the nucleus of the yarn, it has been observed that most of the fibres are concentrated towards the yarn axis, with maximum packing density at the nucleus of the yarn and gradually reducing towards the surface of the yarn. Consequently, the packing density is not uniform across the cross-section of the resultant yarn and most of the fibres are placed in 30% of the area of cross-section in ring spun yarn. Moreover, since the fibres at the surface are lesser, yarn tends to wear out in repeated washes and the fabric becomes fuzzy and dull. 
     In light of the above drawbacks, there is a need to manufacture yarns with a uniform packing density across the cross-section of the yarn. Also, there is a need to manufacture soft fabrics with a loop configuration that has improved and sustainable stability. In addition, there is a need to manufacture fabrics that exhibit high bulkiness, improved softness, less hairiness and superior absorbency with uniformity of texture and appearance after prolonged use. 
     SUMMARY OF THE INVENTION 
     A process for manufacturing a multinuclueus yarn is provided, in accordance with various embodiments of the present invention. The process comprises drawing at least three or more rovings parallelly in a spinning frame such that distance between the extreme right, middle and extreme left rovings is maintained at a first predetermined distance. Further, a separation distance between at least two rovings is maintained at a second predetermined distance. Further, the process comprises partially twisting the parallelly drawn three or more rovings such that at least three primary spinning triangles are formed for each of the parallelly drawn three or more rovings. The three primary spinning triangles are disposed within a first predetermined range of angles respectively. Furthermore, the process comprises combining and twisting the partially twisted three or more rovings such that a fourth resultant spinning triangle is formed within a predetermined distance from each of the three primary spinning triangles. The fourth resultant spinning triangle disposed at a second predetermined range of angles. The twisting of the partially twisted yarn results in a yarn with multiple nucleus formed at three or more zones throughout the cross-section of the resultant yarn. 
     In an embodiment of the present invention, at least three primary spinning triangles are formed with two or more different spinning triangle geometries having at least two different shapes and dimensions. 
     A multinucleus yarn is provided in accordance with various embodiments of the present invention. The multinucleus yarn comprises multiple distinct nuclei having fibres distributed across the multiple distinct nuclei throughout the cross-section of the yarn. The multinucleus yarn further comprises fibres recessed within the yarn. 
     In an embodiment of the present invention, the multinucleous yarn has three or more distinct nuclei having fibres distributed across the three or more distinct nuclei throughout the cross-section of the yarn. In another embodiment of the present invention, the multinucleous yarn has uniform packing density throughout the cross-section of the yarn. 
     A multinucleus yarn formed by the process of claim  1  is provided in accordance with various embodiments of the present invention. A terry fabric obtained from a multinucleus yarn manufactured by the process of claim  1  is provided in accordance with various embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
       The present invention is described by way of embodiments illustrated in the accompanying drawings wherein: 
         FIG. 1 a    illustrates a cross-section of a yarn with improved packing density manufactured in accordance with various embodiments of the present invention; 
         FIG. 1 b    illustrates a cross-section of a prior art yarn; 
         FIG. 1 c    illustrates a longitudinal view of a yarn with improved packing density, in accordance with various embodiments of the present invention; 
         FIG. 1 d    illustrates a longitudinal view of a prior art yarn; 
         FIG. 2  illustrates a ring spinning frame with a roving feed arrangement, in accordance with various embodiments of the present invention; and 
         FIGS. 3, 3   a  and  3   b  illustrate primary spinning triangles and a final spinning triangle formed in accordance with various embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides for a yarn manufactured with uniform or substantially uniform distribution of packing density throughout the cross-section of the yarn. The present invention also provides for fabrics (e.g.) towels produced from the manufactured yarn which exhibits enhanced stability of loop structures formed in the towel. Further, the yarn manufactured in accordance with various embodiments of the present invention may also be used for other fabrics for apparels, denims, bed sheets and other end uses as a superior yarn is produced in terms of strength, evenness, hairiness and imperfections. 
     The disclosure is provided in order to enable a person having ordinary skill in the art to practice the invention. Exemplary embodiments herein are provided only for illustrative purposes and various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. The terminology and phraseology used herein is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed herein. For purposes of clarity, details relating to technical material that is known in the technical fields related to the invention have been briefly described or omitted so as not to unnecessarily obscure the present invention. 
     The present invention would now be discussed in context of embodiments as illustrated in the accompanying drawings. 
       FIG. 1 a    illustrates a cross-section of a multinucleus yarn which is manufactured in accordance with various embodiments of the present invention. As depicted in  FIG. 1   a,  the packing density of the yarn  102   a  is uniform across the cross-section of the yarn  102   a  (illustratively represented by figure numerals  102   a   1 ,  102   a   2 , and  102   a   3 ). That is, in the multinucleus yarn manufactured, in accordance with the various embodiments of the present invention, the fibres do not tend to migrate towards the center of the yarn that result in its concentration around the central axis of the yarn, which is the region of minimum strain, as depicted by a cross-section of a prior art yarn  102   b  in  FIG. 1 b    (illustratively represented by figure numeral  102   b   1 ). In prior art yarns, as represented in  FIG. 1   b,  parallel fibres are twisted as a result of which a torsion is applied and every fibre tries to take the path of minimum strain i.e. towards central axis, which causes all the fibres to move towards the center of the yarn. In the manufactured multinucleus yarn of the present invention, as shown in  FIG. 1   a,  the fibres are distributed uniformly throughout the cross-section of the yarn across the surface due to three nuclei of the yarn (illustratively represented by figure numerals  102   a   1 ,  102   a   2 , and  102   a   3 ) rather than one central axis as in the prior art yarns represented in  FIG. 1   b.  This uniformity in packing density in the across the cross-section of the yarn has resulted in a yarn  102   a  with very high bulk, enhanced softness and low hairiness. 
     Further, it has been observed that a yarn with uniform packing density across the cross-section provides for increased stability of a loop when a loop structure is formed in a fabric made out of the yarn, in accordance with various embodiments of the present invention. For instance, a towel manufactured in accordance with the present invention exhibits extremely high bulkiness, high softness, high absorbency, and a fuzz free or hairiness free uniform surface. Further, the aforementioned characteristics are retained after several washings which is highly desirable and is demonstrative of a good quality soft terry fabric.  FIG. 1 c    depicts a longitudinal view of the yarn manufactured in accordance with various embodiments of the present invention. It can be seen in  FIG. 1   c,  the packing density is distributed substantially uniformly across the cross-section of the yarn  102   c  (illustratively represented by figure numerals  102   c   1 ,  102   c   2 , and  102   c   3 ).  FIG. 1 d    illustrates a prior art longitudinal view of a yarn with prior art yarn  102   d.  As depicted in  FIG. 1   d,  the packing density in the prior art towel is mainly concentrated at the center (illustratively represented by figure numerals  102   d   1 ). 
     In accordance with various embodiments of the present invention, the yarn  102   a,    102   c  with uniform packing density across the cross-section of the yarn is manufactured by a process as provided herein below. 
     It has been observed through extensive research and intuitive experimentations that spacing between rovings that are fed into a ring spinning frame plays a very vital role in the arrangement of fibres or packing density of the yarn as the said spacing affects yarn properties. Referring to  FIG. 2 , in accordance with various embodiments of the present invention, a special arrangement of feed is provided in an illustrative ring spinning frame  200  such that a conventional one roving feed is converted into a three roving feed. In particular, in an embodiment of the present invention, three or more rovings are fed from a back drafting roller  204  (feed roller) of a roller drafting system  202  of the ring spinning frame  200  through a guide holder  204   a.  The guide holder  204   a  is a newly designed guide holder  204   a  which provisions for inserting at least two rovings through one orifice of the guide holder  204   a  of the two or more orifices disposed on the guide holder  204   a  of the ring spinning frame  200 . The three or more rovings are drawn through the roller drafting system  202  such that the strands of the rovings are caused to be drawn parallel to each other. Distance between the extreme right roving and extreme left roving and distance between middle roving to extreme left roving is maintained at a first predetermined distance. Further, a separation distance between the at least two rovings inserted through the orifice is maintained at a second predetermined distance. In an exemplary embodiment of the present invention, distance between the extreme right roving, middle roving and the extreme left roving is maintained at a maximum of 30 mm. In another exemplary embodiment of the present invention, the separation distance between the at least two rovings inserted through the orifice is maintained at at least 4 mm. 
     Table 1 illustratively provides the various process parameters such as yarn count, roving hank, draft, RTR speed, spacer, RTR, R/F spindle speed that are applied to manufacture the yarn with uniform packing density in accordance with an exemplary embodiment of the present invention. Parameters such as roving hank and draft depend on count of final yarn, for example, 0.55 count roving is used for 10 sNe count to 20 s Ne count. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
            
               
                   
                 Yarn Count 
                 Ne 10 s-30 s 
               
               
                   
                 Roving Hank 
                 0.55-2.0 
               
               
                   
                 Draft 
                 30-60 
               
               
                   
                 RTR Speed 
                 15-35 meter/sec 
               
               
                   
                 Spacer 
                 3-6 mm 
               
               
                   
                 RTR 
                 12 nos to 6/0 
               
               
                   
                 R/F spindle speed 
                 8000-18000 rpm 
               
               
                   
                   
               
            
           
         
       
     
     The three or more rovings are then drafted and partially twisted using an individual spinning triangle at the front drafting roller  206  (front roller). The partial twisting introduced at this stage of rotation includes formation of a spinning triangle for each of the three or more rovings at the output of the front roller. The twisting of the three or more parallely drawn rovings with the predetermined maximum distance between the extreme right and extreme left rovings and the predetermined separation distance affects the geometric shape of a twisting triangular area and a distribution status of fibers in the triangular area as illustrated in  FIGS. 3, 3   a  and  3   b.  In an exemplary embodiment of the present invention, the partially twisted components are combined and twisted with predetermined tension and twist multiplier parameters that result in formation of three primary spinning triangles and a fourth final spinning triangle. In particular, as illustrated in  FIGS. 3 and 3   a  a left primary spinning triangle, a right primary spinning triangle and a middle primary spinning triangle is formed for each of the three or more rovings. 
     In various exemplary embodiments of the present invention, the three primary triangles are formed with two or more different spinning triangle geometries having at least two different shapes and dimensions. The vertices of the three primary spinning triangles form one resultant fourth final triangle, as shown  FIG. 3   b.  In an exemplary embodiment of the present invention, the left primary spinning triangle, right primary spinning triangle and the middle primary spinning triangle are disposed at angles that vary between a predetermined range of 9 degrees to 20 degrees. The angle (α), as demonstrated in  FIG. 3   b,  of the fourth final triangle may range between 15 degrees to 44 degrees. In this exemplary embodiment of the present invention, the fourth resultant spinning triangle is formed within a radial distance of 16 mm from the vertices of each of the primary spinning triangles. 
     In this embodiment of the present invention, the fibre migration during the partial twisting of each of the rovings is caused to take place around the three individual spinning axis of each of the primary spinning triangles formed for each of the rovings. As a result, a first yarn component is formed with multiple nuclei which are formed at three or more zones within the cross-section of the resultant yarn. The partially twisted three or more rovings are thereafter drawn to be merged to a ring spindle, having a lappet and traveller arrangement. In particular, after primary spinning triangles are formed and partly twisted, a final spinning triangle is made to convert all strands in one output. Thereafter, it is passed through lappet and ring over traveller to obtain the final twisted yarn. The final twisted yarn is the resultant multinucleus yarn. The lappet is designed to lead the yarn centrally over the spindle axis through rotation of the rovings at a predetermined speed of the traveller rotating over the ring. In an exemplary embodiment of the present invention, the traveller rotates at a speed of 15-35 m/s. The traveller imparts twist to the yarn and enables winding of yarn on to a bobbin. The length wound on the bobbin per unit time corresponds to the difference between speed of spindle and traveller and it is equal to the front roll delivery speed. The speed difference is due to a traveler lag since the traveller does not have a drive of its own but is dragged along behind the spindle. Further, speed of the spindle and the roller drafting system is adjusted as per the twist multiplier (TM) and operational performance. In an exemplary embodiment of the present invention, the speed of the spindle and roller drafting system is between 8000-18000 rpm. At the same R/F rpm, increasing TM reduces the productivity, and vice versa, but strength of the yarn increases. The spindle speed is therefore increased accordingly to maintain desired productivity. Various atmospheric conditions such as humidity and temperature is maintained based on the characteristics of the fibres of the rovings. Further, a filament, yarn, or any other element may be fed at the front roller to enhance one or more features of the resultant yarn. In the resultant multinucleus yarn, manufactured using the process mentioned above, the tendency of the fibre to move towards the nucleus is restricted and the distribution of fibre or packing density is uniform or substantially uniform throughout the cross-section of the resultant yarn. That is, as the fibres are distributed across multiple distinct nuclei, fibres move toward each of the multiple distinct nuclei, and not towards the central nucleus, and the resultant yarn formed is a multinucleus yarn with multiple nucleus of packing density core. In an exemplary embodiment of the present invention, fibres are distributed across three distinct nuclei throughout the cross-section of the yarn. Consequently, the packing density of the resultant yarn is uniform throughout the cross-section of the resultant yarn. Uniform distribution of the packing density translates into an increase in the distribution of fibres throughout the cross-section of the yarn. This uniform distribution contributes to the strength of the yarn which is highly desirable as it enhances strength of the yarn by positively impacting one or more yarn characteristics. In turn, a terry fabric that is produced from the manufactured yarn exhibits enhanced stability of loop structures which are formed on the terry fabric. Further, since the three primary spinning triangles include protruding fibres that causes hairiness, when combined in to one, the protruding fibres are substantially enclosed inside the resultant multinucleus yarn such that the fibres are recessed within the yarn, and hairiness is significantly reduced. Consequently, major operational and qualitative advantage is afforded in the production of the terry fabric from the resultant yarn. 
     Advantageously, the manufactured multinucleus yarn having multiple nucleus provides for high bending rigidity, enhanced softness and bulkiness and sustainable yarn geometry, which in turn lends to increased strength and less hairiness of fabrics produced from the manufactured yarn. Further, the manufactured yarn may also be used for producing fabrics used for denim, apparel, home furnishing, bed sheets etc. as it exhibits superior qualities in terms of uniformity of appearance, higher piling resistance and higher fabric strength. Further, this is achieved using the same quality of fibre and by simply changing the process of spinning, therefore, providing a cost advantage. This is advantageous over conventional methods which require better grade of cotton fibres to achieve the said qualities that causes wastage and high cost of manufacturing. 
     While the exemplary embodiments of the present invention are described and illustrated herein, it will be appreciated that they are merely illustrative. It will be understood by those skilled in the art that various modifications in form and detail may be made therein without departing from or offending the spirit and scope of the invention as defined by the appended claims.