Abstract:
The present invention provides a sparkling dyed double covered yarn comprising: (i) a core yarn; (ii) a first sheath yarn made of a bright polyamide yarn wound around the core yarn to form a single covered yarn; and (iii) a second sheath yarn made of a dyed polyamide yarn wound around said single covered yarn to form a double covered yarn; wherein the first sheath yarn and the second sheath yarn are wound in the same direction. The invention further provides processes for manufacturing a sparkling dyed double covered yarn and fabrics comprising the same.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a double-covered yarn having a sparkling effect, a process for making the same, and fabric comprising such a yarn. More specifically, the invention relates to a double covered sparkling yarn comprising a core yarn, a first flat bright polyamide sheath yarn and a second dyed polyamide sheath yarn, wherein the first and the second sheath yarn are wound around the core yarn in the same direction. 
       BACKGROUND OF THE INVENTION 
       [0002]    Nowadays, numerous textile applications employ covered yarns, such as single covered yarns obtained by winding a sheath yarn around a core yarn, and double-covered yarns obtained by further winding around the single covered yarn a second sheath yarn. When an elastomeric core yarn is employed, the resulting covered yarn may be employed for manufacturing stretch fabrics for various applications, for instance in the field of hosiery, underwear, socks, upper wear, and sportswear. A process for the production of double covered elastomeric yarn is disclosed for instance in U.S. Pat. No. 6,240,716, wherein a spandex core is covered with a first sheath yarn to form a single covered yarn, and a second sheath yarn is wound around the single covered yarn. 
         [0003]    However, in some textile applications such as hosiery, yarns having a sparkling effect may be of interest. In this case the air-jet entangling method is preferably used as it enables the production of yarns having a better luster. Air-jet entangling as a covering process for spandex elastomeric yarn is described for instance in U.S. Pat. No. 3,940,917. However, air-jet covered composite yarns present some drawbacks. Specifically, such composite yarns have loops extending from the covering component which partially obscure knitted stitch openings, resulting in a more opaque look to knitted hosiery. Further, in knitted hosiery the extending loops increase the likelihood that difficulties will be encountered during the knitting operation and when the finished hosiery is in use. 
         [0004]    Therefore, there is a need for a simple and cost effective process for producing dyed yarns having a sparkling effect and which can be easily knitted. 
         [0005]    It is thus an object of the invention to provide a yarn having both a homogeneous color and a sparkling effect all along the yarn. 
         [0006]    It is another object of the invention to provide a dyed sparkling yarn for use in the textile industry, especially for hosiery and fashionable knitted garments. 
         [0007]    It is still another object of the invention to provide a process for manufacturing a dyed sparkling yarn. 
         [0008]    It is still another object of the invention to provide a fabric made of a dyed sparkling yarn. 
         [0009]    Further purposes and advantages of this invention will appear as the description proceeds. 
       SUMMARY OF THE INVENTION 
       [0010]    In a first aspect, the present invention provides a sparkling dyed double covered yarn comprising: 
         [0000]    (i) a core yarn;
 
(ii) a first sheath yarn made of a bright polyamide yarn wound around the core yarn to form a single covered yarn; and
 
(iii) a second sheath yarn made of a dyed polyamide yarn wound around said single covered yarn to form a double covered yarn; wherein the first sheath yarn and the second sheath yarn are wound in the same direction.
 
         [0011]    In some specific embodiments of the double covered yarn of the invention, the core yarn is an elastomeric yarn, such as a spandex yarn. 
         [0012]    In some specific embodiments of the double covered yarn of the invention, the first sheath yarn is a bright flat polyamide yarn, especially a bright flat fully drawn polyamide yarn (FDY). In some other embodiments, the first sheath yarn is a bright partially oriented polyamide yarn (POY) or a bright textured polyamide yarn. 
         [0013]    In some specific embodiments of the double covered yarn of the invention, the second sheath yarn is a dyed textured polyamide yarn, a dyed flat polyamide yarn, or a dyed POY yarn. 
         [0014]    In some specific embodiments of the double covered yarn of the invention, the number of turns per meter of the bright polyamide yarn is between 300 and 1800 turns per meter. 
         [0015]    In some specific embodiments of the double covered yarn of the invention, the number of turns per meter of the dyed polyamide yarn is between 300 and 1800 turns per meter. 
         [0016]    A particular embodiment of the sparkling dyed double covered yarn of the invention comprises: 
         [0000]    (i) an elastomeric core yarn;
 
(ii) a first sheath yarn made of a bright flat fully drawn polyamide yarn wound around the core yarn to form a single covered yarn; and
 
(iii) a second sheath yarn made of a dyed textured polyamide yarn wound around said single covered yarn to form a double covered yarn; wherein the first sheath yarn and the second sheath yarn are wound in the same direction.
 
         [0017]    In a second aspect, the invention provides a process for manufacturing a sparkling dyed double covered yarn comprising the steps of: 
         [0000]    (i) providing a core yarn;
 
(ii) winding a first sheath yarn made of a bright polyamide yarn around said core yarn to form a single covered yarn; and
 
(iii) winding a second sheath yarn made of a dyed polyamide yarn around said single covered yarn to form a double covered yarn; wherein the first and the second sheath yarn are wound in the same direction.
 
         [0018]    In some specific embodiments of the process of the invention, the core yarn is an elastomeric yarn, such as a spandex yarn. 
         [0019]    In some specific embodiments of the process of the invention, the first sheath yarn is a bright flat polyamide yarn, especially a bright flat fully drawn polyamide yarn (FDY). In some other embodiments, the first sheath yarn is a bright partially oriented polyamide yarn (POY) or a bright textured polyamide yarn. 
         [0020]    In some specific embodiments of the process of the invention, the second sheath yarn is a dyed textured polyamide yarn, a dyed flat polyamide yarn, or a dyed POY yarn. 
         [0021]    In some specific embodiments of the process of the invention, the winding speed of the bright polyamide yarn is between 300 and 1800 turns per meter. 
         [0022]    In some specific embodiments of the process of the invention, the winding speed of the dyed polyamide yarn is between 300 and 1800 turns per meter. 
         [0023]    In a third aspect, the invention provides a fabric comprising a sparkling dyed double covered yarn as described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The above and other characteristics and advantages of the invention will be more readily apparent through the following examples, and with reference to the appended drawings, wherein: 
           [0025]      FIG. 1  is a drawing showing the structure of an embodiment of the double covered yarn of the invention ( 40 ): core yarn ( 10 ), bright yarn ( 20 ) and dyed yarn ( 30 ); and 
           [0026]      FIG. 2  is a drawing showing an embodiment of the double cover process of the invention: core yarn feeding bobbin ( 1 ), core yarn ( 10 ), bright yarn bottom spool ( 2 ), bright yarn ( 20 ), dyed yarn upper spool ( 3 ), dyed yarn ( 30 ), double covered yarn ( 40 ), double covered yarn receiving bobbin ( 4 ). 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    It has been surprisingly found by the inventors that a sparkling colored yarn can be obtained by winding a first bright sheath yarn around a core yarn, and by further winding a second dyed sheath yarn around the first bright sheath yarn, the first and the second sheath yarn being wound in the same orientation. The resulting double covered yarn can be easily knitted into fabrics which show both a homogenous color and a uniformly distributed sparkling effect. 
         [0028]    As used herein, the terms “core yarn” or “core fiber” refer to a central yarn around which a first and a second sheath yarns are wound. The core yarn may be elastomeric or non-elastomeric. In a specific embodiment of the invention, the core yarn is a spandex yarn. 
         [0029]    The term “spandex” and “elastan” are used interchangeably and means a manufactured fiber in which the fiber-forming substance is a long chain synthetic elastomer comprised of a polyurethane-polyurea copolymer. Spandex in the range of about 11 to 350 decitex is suitable for use in making the double covered yarn of the present invention. 
         [0030]    As used herein, the expression “sheath yarn” means a yarn comprising continuous filaments, bundled staple fibers, or spun staple fibers, or both filaments and staple fibers. 
         [0031]    The “first sheath yarn” is the sheath yarn wound around the core yarn to form a single covered yarn. Suitable first sheath yarns for use in the present invention are bright flat yarns (especially fully drawn yarn FDY), bright partially oriented (POY) polyamide yarns or bright textured yarns. First sheath yarns may have a round, an oval or a trilobal cross-section. Examples of suitable first sheath bright yarns for use in the present invention are Nylon 6.6 FLAT 22/7 BR trilobal (Nilit®Fibers), Nylon 6.6 FLAT 17/4 BR oval (Nilit®Fibers), Nylon 6.6 FLAT 17/3 BR trilobal (Nilit®Fibers) and Nylon 6.6 FLAT 44/34 BR trilobal (Nilit®Fibers), Nylon 6.6 POY 27/7 BR trilobal (Nilit®Fibers), Nylon 6.6 POY 17/3 BR trilobal (Nilit®Fibers), Nylon 6.6 POY 22/7 BR trilobal (Nilit®Fibers) and Nylon 6.6 POY 27/12 BR trilobal (Nilit®Fibers). 
         [0032]    The “second sheath yarn” is the sheath yarn wound around the single covered yarn to form a double covered yarn. Examples of suitable second sheath yarns for use in the present invention are made of natural or dyed polyamide (e.g. spin dyed polyamide), and can be either textured, flat or POY yarns. An example of a suitable second sheath yarn for use in the present invention is the Nylon 6.6 TEXTURED 44/34/1 BK (spin-dyed black yarn) from Nilit®Fibers. 
         [0033]    The terms “bright”, “brilliant”, “shiny”, and “glossy” are used herein interchangeably and refer to the glossy effect of the first sheath yarn. The term “sparkling” is used herein to define the effect produced by the double covered yarn of the invention (which is comparable to the sparkling of a diamond), this effect resulting from the specific arrangement of the two sheath yarns (a dyed yarn and a bright yarn) around the core yarn. 
         [0034]    The first and second sheath yarns of the sparkling double covered yarn of the present invention have an identical twist orientation, i.e. both in the z-direction or both in the s-direction ( FIG. 1 ). In the method of the invention the first sheath yarn wound around the core yarn is made of a bright polyamide yarn, whereas the second sheath yarn wound around the first sheath is made of a dyed polyamide yarn. This allows a uniform distribution of the color and the shining effect along the double-covered yarn and generates a uniform sparkling effect along the manufactured yarn. The number of twists (or turns) of each of the first sheath yarn and the second sheath yarn may be similar or different according to the intensity of the sparkling effect which is required (i.e. more or less shiny, more or less colored). For instance, if the number of twists of the bright sheath yarn is more important than the number of twists of the dyed sheath yarn, the resulting double covered yarn is shinier and less color effect is perceptible. 
         [0035]    The sparkling double covered yarn of the invention may be manufactured with any standard double covering machine. A bright polyamide yarn is placed on a bottom spool and a dyed polyamide yarn is placed on an upper spool ( FIG. 2 ). The core yarn enters the machine from the bottom and is first covered with the flat bright sheath polyamide yarn at about 300-1800 turns per meter to form a single covered yarn. The single covered yarn is then covered with the second dyed sheath polyamide yarn, which is wound in the same direction is about 300-1800 turns per meter. The number of twists per meter and the winding speed of each of the bright yarn and the dyed yarn may be adjusted so as to obtain the desired sparkling effect. 
         [0000]    The present invention is further described by the following examples which are not intended to limit the scope of the present invention, which scope is defined by the appended claims. 
       Example 1 
       [0036]    In this example, production of a sparkling black double covered yarn was done on a double covering machine Menegatto model 1500, with the following covering settings and yarn properties: 
         [0000]                                                                                                                  Core Yarn   First sheath yarn   Second sheath yarn                                    Reference   PA 66 17Dtex   Nylon 6.6 FLAT   Nylon 6.6 TXT           Mobilon ™   22/7 BR   44/34/1 Black           (Nisshinbo   (Nilit ®Fibers)   (Nilit ®Fibers)           Chemical)            Speed   1600   m/min   1600   m/min   1400   m/min       Tension   4   g   4   g   8   g            Turns per   NA   800   800       meters (tpm)                    
The core yarn has the following characteristics: draw ratio of elastan 3.00, tenacity 3.9 cN/dtex, elongation 43.3%, and 1% oil. The Nylon 6.6 FLAT 22/7 BR is a fully drawn yarn (FDY).
 
As a result of the above process, a sparkling black double covered elastic yarn was produced according to the method above. This sparkling black double covered yarn glistens with a delicate, refined shine and may be further used for the manufacture of fashionable knitted stretch garments.