Abstract:
Slasher machines and rope dyeing machines are the main dyeing machine that is used to continuously dye yarn fabrics for denim using indigo dyes. In denim dyeing, indigo (blue color VAT) and some sulfur dyes are mixed together to achieve blue/black/brown color denim fabrics. This invention is the achievement of dyeing reactive/direct/pigment/acid/disperse and other non VAT/sulfur OR its combinations of non VAT/sulfur dyes OR combinations between VAT/sulfur dyes and VAT/sulfur dyes on continuous yarn dyeing machines and relevant apparatus. Its products are also very distinguishable, especially its combinations, hence is a part of the invention.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of U.S. Provisional Application No. 61/820,716 filed May 8, 2013, the whole of which is hereby incorporated by reference herein. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates to a multi-colored yarns and a fabric made of the multi-colored yarns. 
       BACKGROUND OF INVENTION 
       [0003]    Denim is a fabric in which the indigo dyed wrap threads are woven with white weft threads. Many techniques have been developed to color demin, for example, piece color coating, tainting/overdyeing and garment dye, etc. However, these coloring techniques cannot give natural and brilliant colors to denim. As a result, there is a need for a new technique for coloring denim which is also environmental friendly. 
       SUMMARY OF INVENTION 
       [0004]    In the light of the foregoing background, it is an object of the present invention to provide an alternative and novel technique in coloring denim (also applies to other fabrics) while preserving the essence of denim. 
         [0005]    Accordingly, the present invention, in one aspect, is a denim comprising:
       1. a plurality of warp threads; and   2. a plurality of weft threads;
 
wherein each warp thread further comprises a first yarn and a dye coating disposed on the first yarn, comprising a plurality of different dyes; each weft thread further consists of a second yarn without any dye thereon; and at least one of the plurality of dyes in the dye coating at least partially reveals and only partially covers another different dye immediately there-below; and the bottom most dye only partially covers the first yarn, such that the dyes are not disposed on at least a portion of the first yarn, thereby showing the wrap thread with a plurality of colors.
       
 
         [0008]    In one embodiment, the plurality of dyes comprises a non-VAT dye and a non-sulfur dye; wherein the non-VAT and the non-sulfur dye are selected from the group consisting of reactive dye, direct dye, pigment dye, acid dye and disperse dye. 
         [0009]    According to another aspect of the present invention, a method of preparing a dyed yarn is disclosed. The method comprises the steps of
       1. continuously passing the yarn through a dyeing machine selected from a group consisting of slasher dyeing machine and rope dyeing machine;   2. dyeing the yarn with a dye coating comprising a plurality of different dyes forming a plurality of different dye layers in the dye coating in a single process/pass-through of the dyeing machine; wherein the plurality of dyes further comprises non-VAT dye, non-sulfur dye, sulfur dye and VAT dye such that the dye coating is a combination of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye; wherein the top most dye layer of the dye coating is formed by a cover dye layer with a single color selected from a group consisting of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye; and   3. performing a post-treatment step configured to remove at least a portion of the dye coating such that at least one of the plurality of dyes in the dye coating at least partially reveals and partially covers another different dye immediately therebelow; and the bottom most dye only partially covers the first yarn, such that the dyes are not disposed on at least a portion of the first yarn, thereby showing the wrap thread with a plurality of colors.       
 
         [0013]    Yet another aspect of dyed yarn of the present invention is a fabric obtained by a process comprising the step of
       1. weaving a dyed yarn obtained by a process comprising the steps of:
           a) continuously passing a yarn through a dyeing machine selected from a group consisting of slasher dyeing machine and rope dyeing machine; and   b) dyeing the yarn with a dye coating comprising a plurality of different dyes forming a plurality of different dye layers in the dye coating in a single process/pass-through of the dyeing machine; wherein the plurality of dyes further comprises non-VAT dye, non-sulfur dye, sulfur dye and VAT dye such that the dye coating is a combination of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye; wherein the top most dye layer of the dye coating is formed by a cover dye layer with a single color selected from a group consisting of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye;   
           2. after the weaving step, performing a post-treatment step configured to remove at least a portion of each dye coating such that at least one the plurality of dyes in the dye coating at least partially reveals and partially covers another different dye immediately therebelow; and the bottom most dye only partially covers the first yarn, such that the dyes are not disposed on at least a portion of the first yarn, thereby showing the wrap thread with a plurality of colors.       
 
         [0018]    There are many advantages to the present invention. In particular, the present invention, the colored denim of the present invention is sharp, crisp and smooth and the color of the denim of the present invention is natural and brilliant. The denim using the coloring technique of this invention has higher quality (e.g. higher contrast, with washing effects, great hand feel, etc) as compared to denim prepared from conventional coloring techniques such as tainting and garment dyeing with. Further, this technique is environmentally friendly and safe with the use of less water and in absence of the use of resin. Application of this technique leads to more cost-efficient productivity, shorter lead time, and great savings in the overall garment process. Furthermore, the novelties of the present invention are listed as follow:
       1. No process of dyeing non VAT/sulfur dye on continuous yarn dyeing machines has ever been achieved.   2. No process of dyeing combination dye types using continuous yarn dyeing machines has been achieved.   3. No process of dyeing of combination dye types using continuous dye machines with indigo has ever been achieved.   4. No continuous yarn dyeing machine (including slash and rope dyeing machines) containing any intermediate drying units has ever been existed.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    For a more complete understanding of the present invention, reference is made to the following detailed description and accompanying drawings, in which: 
           [0024]      FIG. 1  shows a cross sectional view of a wrap yarn according to one embodiment of the present invention; 
           [0025]      FIG. 2  shows a top view of a wrap yarn according to the same embodiment of the present invention; 
           [0026]      FIG. 3  shows a side view of a wrap yarn according to the same embodiment of the present invention; 
           [0027]      FIG. 4  shows a denim after surface color coated treatment compared to the denim of the present invention; 
           [0028]      FIG. 5  shows a denim after tainting/overdyeing treatment compared to the denim of the present invention; 
           [0029]      FIG. 6  shows a denim after piece dyeing treatment compared to the denim of the present invention; and 
           [0030]      FIG. 7  shows a denim after garment dyeing treatment compared to the denim of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    As used herein and in the claims, “comprising” means including the following elements but not excluding others. 
         [0032]    Now referring to  FIG. 1 ,  FIG. 2  and  FIG. 3 , the present invention, in one aspect is, a denim comprising a plurality of wrap threads  20  and a plurality of weft threads. Each of the wrap threads  20  further comprises a first yarn  22  and a dye coating that is disposed on the first yarn  22 , in which the dye coating comprises a plurality of different dyes. At least one of the plurality of dyes in the dye coating (i.e. first dye  24 ) at least partially reveals and only partially covers another different dye immediately there-below (i.e. second dye  26 ); and the bottom most dye (i.e. second dye  26 ) only partially covers the first yarn  22 , such that the dyes (i.e. both first dye  24  and second dye  26 ) are not disposed on at least a portion of the first yarn  22 , thereby showing the wrap thread with a plurality of colors. Each weft thread only consists of a second yarn without any dye thereon. 
         [0033]    In an exemplary embodiment, each of the wrap threads  20  further comprises a polymer type coating on the first yarn  22  configured to increase wet crock fastness. 
         [0034]    In another embodiment, the plurality of dyes comprises a non-VAT dye and a non-sulfur dye; wherein the non-VAT and the non-sulfur dye are selected from the group consisting of reactive dye, direct dye, pigment dye, acid dye and disperse dye. 
         [0035]    In yet another embodiment, the plurality of dyes further comprises a VAT dye and a sulfur dye such that the dye coating is a combination of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye; wherein the VAT dye is indigo and forms the top most dye layer. 
         [0036]    Accordingly to yet another aspect of the present invention, a method of preparing a dyed yarn comprises the steps of (a) continuously passing the yarn through a dyeing machine selected from a group consisting of slasher dyeing machine and rope dyeing machine; (b) dyeing the yarn with a dye coating comprising a plurality of different dyes forming a plurality of different dye layers in said dye coating in a single process/pass-through of the dyeing machine; wherein the plurality of dyes further comprises non-VAT dye, non-sulfur dye, sulfur dye and VAT dye such that the dye coating is a combination of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye; wherein the top most dye layer of the dye coating is formed by a cover dye layer with a single color selected from a group consisting of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye; and (c) performing a post-treatment step configured to remove at least a portion of the dye coating such that at least one the plurality of dyes in the dye coating at least partially reveals and partially cover another different dye immediately therebelow; and the bottom most dye only partially covers the first yarn, such that the dyes are not disposed on at least a portion of the first yarn, thereby showing the wrap thread with a plurality of colors. 
         [0037]    In one embodiment, the continuously passing step further comprises the steps of (a) absorbing and fixing a polymer on the yarn; and (b) coating the polymer on the yarn. The polymer is selected from a group consisting of polyurethane, poly-acrylic, polyethylene, and silicone polymer. The post-treatment step is performed at a pre-fabrication stage or a fabric making stage or a garment making stage; and the post-treatment step is selected from a group consisting of bleaching, abrasion, oxidation and reduction. 
         [0038]    In yet another aspect of the present invention, a dyed yarn obtained by a process comprising the steps of (a) continuously passing the yarn through a dyeing machine selected from a group consisting of slasher dyeing machine and rope dyeing machine; (b) dyeing the yarn with a dye coating comprising a plurality of different dyes forming a plurality of different dye layers in said dye coating in a single process/pass-through of the dyeing machine; wherein the plurality of dyes further comprises non-VAT dye, non-sulfur dye, sulfur dye and VAT dye such that the dye coating is a combination of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye; wherein the top most dye layer of the dye coating is formed by a cover dye layer with a single color selected from a group consisting of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye; and (c) performing a post-treatment step configured to remove at least a portion of the dye coating such that at least one the plurality of dyes in the dye coating at least partially reveals and partially cover another different dye immediately therebelow; and the bottom most dye only partially covers the first yarn, such that the dyes are not disposed on at least a portion of the first yarn, thereby showing the wrap thread with a plurality of colors. 
         [0039]    In one embodiment, the continuously passing step further comprises the steps of (a) absorbing and fixing a polymer on the yarn; and (b) coating the polymer on the yarn. The polymer is selected from a group consisting of polyurethane, poly-acrylic, polyethylene, and silicone polymer. The post-treatment step is performed at a pre-fabrication stage or a fabric making stage or a garment making stage; and the post-treatment step is selected from a group consisting of bleaching, abrasion, oxidation and reduction. 
         [0040]    In yet another aspect of the present invention, a fabric obtained by a process comprising the steps of weaving the dyed yarn obtained by a process comprising the steps of (i) continuously passing the yarn through a dyeing machine selected from a group consisting of slasher dyeing machine and rope dyeing machine; and (ii) dyeing the yarn with a dye coating comprising a plurality of different dyes forming a plurality of different dye layers in said dye coating in a single process/pass-through of the dyeing machine; wherein the plurality of dyes further comprises non-VAT dye, non-sulfur dye, sulfur dye and VAT dye such that the dye coating is a combination of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye; wherein the top most dye layer of the dye coating is formed by a cover dye layer with a single color selected from a group consisting of the VAT dye, the sulfur dye, the non-VAT dye and the non-sulfur dye. And after the weaving step, performing a post-treatment step configured to remove at least a portion of each the dye coating such that at least one the plurality of dyes in the dye coating at least partially reveals and partially cover another different dye immediately therebelow; and the bottom most dye only partially covers the first yarn, such that the dyes are not disposed on at least a portion of the first yarn, thereby showing the wrap thread with a plurality of colors. 
         [0041]    In one embodiment, the continuously passing step further comprises the steps of (a) absorbing and fixing a polymer on the yarn; and (b) coating the polymer on the yarn. The polymer is selected from a group consisting of polyurethane, poly-acrylic, polyethylene, and silicone polymer. The post-treatment step is performed at a fabric stage or a garment making stage; and the post-treatment step is selected from a group consisting of bleaching, abrasion, oxidation and reduction. 
         [0042]    Further, continuous of yarn dyeing machine of non VAT/sulfur dyeing does not exist. Also, continuous of yarn dyeing machine of combination of VAT/sulfur dye and non VAT/sulfur dyeing does not exist. 
         [0043]    The configuration of dyeing non VAT/sulfur dye yarn on continuous machines requires intermediate drying, intermediate heating, additional bath slots, additional heating sensors, specialized designed heated rollers. 
         [0044]    By this invention, greige yarn or colored yarn can be the input of the dyeing system and the output will be a dyed yarn using non VAT/sulfur dye yarn. 
         [0045]    In slash or rope dyeing, no machines uses intermediate heating. 
         [0046]    Greige yarn or colored yarn can be the input of the continuous system. Once entered, the desired combination of dyes (non VAT/sulfur dye)/auxiliaries will be set into the water basins. Yarn will be passed through the basins by picking up non VAT/sulfur dye and its auxiliaries. Through the cycle of the machine with intermediate heating, drying and re-wetting, the non VAT/sulfur dye with its auxiliaries will be reacted/fixed onto the yarn. The output of the system will be colored yarn. 
         [0047]    By creating a recombination of the mentioned process, the output can be colored yarn with different dye types, for example, indigo with reactive, indigo with direct, reactive with direct, pigment with reactive etc. The combination of such can also be created by replacing greige yarn with colored yarn in the input process, for example, the input is to be reactive dyed yarn and the output can be pigment yarn with reactive dyed yarn. 
         [0048]    Combination dyeing of the mentioned process can be used on piece dyes to create combination of dyeing. 
         [0049]    In another embodiment, the process of dyeing yarn using slasher dyeing machines, rope dyeing machines or other continuous dyeing machines use the following dye types:
       1. reactive dye;   2. direct dye;   3. pigment dye;   4. acid dye;   5. disperse dye.       
 
         [0055]    The output fabrics consist of the following:
       1. Weaved fabric using reactive dyed yarn using continuous yarn dyeing;   2. Weaved fabric using direct dyed yarn using continuous yarn dyeing;   3. Weaved fabric using pigment dyed yarn using continuous yarn dyeing;   4. Weaved fabric using acid dyed yarn using continuous yarn dyeing;   5. Weaved fabric using disperse dyed yarn using continuous yarn dyeing;   6. Weaved fabric using combination dyed yarn of the aforementioned weaved fabric of 1, 2, 3, 4, 5 using continuous yarn dyeing;   7. Weaved fabric using combination dyed yarn of the aforementioned weaved fabric of 1, 2, 3, 4, 5 together with VAT (including indigo) or sulfur dye using continuous yarn dyeing;   8. Any combination of the aforementioned weaved fabric of 1, 2, 3, 4, 5, 6, 7.       
 
         [0064]    In yet another embodiment, the process of dyeing fabric using continuous dyeing machine (yarn dye or piece dye) uses the following dye type or combination thereof:
       1. Reactive with pigment;   2. Reactive with direct;   3. Vat (including indigo) with reactive;   4. Vat (including indigo) with direct;   5. Vat (including indigo) with pigment;   6. Combination of the aforementioned dye types  3 ,  4 ,  5  together with sulfur dye;   7. direct with pigment.       
 
         [0072]    The output fabrics consist of the following:
       1. Weaved reactive dyed with pigment dye combination using continuous piece dyeing;   2. Weaved reactive dyed with direct dye combination using continuous piece dyeing;   3. Weaved reactive dyed with VAT (including indigo) dye combination using continuous piece dyeing;   4. Weaved direct dyed with VAT (including indigo) dye combination using continuous piece dyeing;   5. Weaved pigment dyed with VAT (including indigo) dye combination using continuous piece dyeing;   6. Combination of the aforementioned fabrics of 1, 2, 3, 4, 5 together with sulfur dye;   7. any combinations of the aforementioned fabrics of 1, 2, 3, 4, 5, 6.       
 
         [0080]    The use of intermediate heating device in continuous yarn dyeing machines includes:
       1. the use of convection heating methods including:
           a) hot air blowing box (area of which yarn passes through an area where hot air is blown);   b) liquid heating box (area of which the yarn passes through an area where hot liquid is blown);   c) steam box (area of which the yarn passes through an area of hot steam);   d) other convection means to heat the yarn.   
           2. The use of conduction heating method including:
           a) Heated corners and non-moving surface (where yarn passes through a non-moving corner where heat is conducted);   b) Heated rollers (where yarn passes through an area in which heat is conducted by rolling cylinders);   c) other conduction means to heat the yarn.   
           3. The use of radiation heating methods including:
           a) optical heaters (where yarn passes through an area in which heat is gen-erated by irradiation of yarn);   b) open flame (where yarn passes through an open flame);   c) infrared heater (where yarn passes through an area in which heat is gen-erated by irradiation of yarn).   
               
 
         [0094]      FIG. 4 ,  FIG. 5 ,  FIG. 6 , and  FIG. 7  show the comparison between the denims of the present invention (shown on the left in  FIG. 4 ,  FIG. 5 ,  FIG. 6 , and  FIG. 7 ) with the denims of conventional dyeing treatment (shown on the right in  FIG. 4 ,  FIG. 5 ,  FIG. 6 , and  FIG. 7 ). As compared with the denims of conventional dyeing treatment, the present invention provides denim with different color layers while reserving white slubs. The colors on the denim of the present invention are natural and brilliant. Also the colors of the denim of the present invention are with high contrast and high color gradient. 
         [0095]    The present invention provides denim with different color layers while having white slubs. The colors on the denim of the present invention are natural and brilliant. Yet other advantages of the present invention are cheap, environment friendly, with high contrast and high color gradient. In addition, the present invention disposes a plurality of dyes on a yarn and allows each of the plurality of dyes to form a dye layers on the yarn, wherein the dye of the top most dye layer is indigo. Moreover, in one embodiment, wherein each dye layer only partially covers a layer immediately there-below and the bottom most dye layer only partially covers the yarn. Furthermore, the yarn is continuously dyed with non-VAT/non-sulfur dyes by a dyeing machine. 
         [0096]    It will thus be seen that the objects set forth above, among those elucidated in, or made apparent from, the preceding description, are efficiently attained and, since certain changes may be made in the above construction and/or method without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing figures shall be interpreted as illustrative only and not in a limiting sense. 
         [0097]    The following claims should not be read as limited to the described order or elements unless stated to that effect. Therefore, all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.