Patent Abstract:
Processes for dyeing fabric are provided. The process can include continuously moving the fabric in a machine direction; removing folds or creases from the fabric; spraying a first surface of the fabric with a dye; and exposing the fabric to atmospheric steam after spraying the dye on the first surface but prior to the dye drying on the first surface so that the dye migrates from the first surface to a second surface of the fabric and reacts with and affixes to a component of the fabric.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit of U.S. Provisional Application No. 60/666,940 filed on Mar. 31, 2005, the contents of which are incorporated by reference herein. This application is a continuation-in-part of U.S. application Ser. No. 10/601,820 entitled Spray Dyeing of Garments and filed on Jun. 23, 2003, the contents of which are incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention is related to fabric dyeing. More particularly, the present invention is related to processes of spray dyeing fabrics.  
         [0004]     2. Description of Related Art  
         [0005]     Today, fabrics are made from a wide-variety of natural fibers, synthetic fibers, and any combination thereof. Many processes have been proposed for dyeing fabrics.  
         [0006]     One process, commonly referred to as yarn dyeing, involves dyeing individual fibers or yarns before the fibers are sewn or knitted into a fabric. One problem associated with such yarn dyeing process relates to inventory control of the yarns and associated garments. For example, yarn dyeing requires the garment manufacturer to maintain a supply of the various colored yarns used in its products. This can lead to an increased cost of goods.  
         [0007]     Another dyeing process is commonly referred to as bulk dyeing. In bulk dyeing, un-dyed fibers or yarns are knitted or woven into a raw or un-dyed fabric. The raw fabric is subsequently dyed. The dyed fabric is then used to make the desired product, such as a garment.  
         [0008]     Some common bulk dyeing processes include vat dyeing, beam dyeing, jet dyeing, and bath dyeing. Vat dyeing typically consists of immersing a piece of fabric in a vat of liquid dye. Beam dyeing involves winding a length of fabric about a perforated beam. The beam is then placed in a vessel where liquid dye is pumped into the center of the beam, out of the perforations, and through the fabric. Jet dyeing involves placing the fabric in a high-pressure, high-temperature kettle of liquid dye. Bath dyeing involves immersing the fabric in a bath of dye, which is contained in a rotating drum.  
         [0009]     One problem associated with bulk dyeing processes relates to the large amounts of water required during processing, which can increase cost of goods for such bulk dyed fabrics.  
         [0010]     Yet another problem with bulk dyed fabrics in the manufacture of garments is related to the unpredictability of consumer color preferences. In the garment industry, change in the consumer&#39;s preference for one color over another color can lead to an overstock of the undesired colored garments and a back order situation of the desired colored garments. Thus, garments made from bulk dyed fabrics have not proven flexible enough to meet increasing and changing consumer demands.  
         [0011]     Further processes of dyeing fabrics involve printing a dye onto a surface of a fabric. This process is commonly used to apply a decorative pattern on the surface of the fabric. Such printing processes include screen-printing and inkjet printing. While these processes have proven useful in quickly changing from one decorative pattern to another, they have not proven useful in bulk dyeing of fabrics.  
         [0012]     Accordingly, there is a continuing need for flexible, low cost, low waste processes of dyeing fabrics.  
       SUMMARY OF THE INVENTION  
       [0013]     It is an object of the present invention to provide processes for continuously dyeing fabric to a substantially uniform color.  
         [0014]     The process can include continuously moving the fabric in a machine direction; removing folds or creases from the fabric; spraying a first surface of the fabric with a dye; and exposing the fabric to atmospheric steam after spraying the dye on the first surface but prior to the dye drying on the first surface so that the dye migrates from the first surface to a second surface of the fabric and reacts with and affixes to a component of the fabric.  
         [0015]     The process can include continuously moving the fabric in a machine direction; opening the fabric and ensuring that the fabric is taut so that any folds or creases in the fabric are substantially removed; spraying a first surface of the fabric with a dye while the fabric is open; and exposing the fabric to atmospheric steam after spraying the dye on the first surface but prior to the dye drying on the first surface so that the dye migrates from the first surface to a second surface of the fabric and reacts with and affixes to a component of the fabric.  
         [0016]     A process for continuously dyeing a tubular fabric is also provided. The process includes opening the tubular fabric; spraying a first surface of the open tubular fabric with a dye; closing the tubular fabric; and exposing the closed tubular fabric to atmospheric steam after spraying the dye on the first surface but prior to the dye drying on the first surface so that the dye migrates from the first surface to a second surface of the tubular fabric and reacts with and affixes to a component of the tubular fabric.  
         [0017]     The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a schematic view of an exemplary embodiment of an automated process for dyeing fabric according to the present invention;  
         [0019]      FIG. 2  is a schematic view of another alternate exemplary embodiment of an automated process for dyeing fabric according to the present invention;  
         [0020]      FIG. 3  is a top schematic view of another alternate exemplary embodiment of an automated process for dyeing fabric according to the present invention;  
         [0021]      FIG. 4  is a side view of the second station of  FIG. 3 ; and  
         [0022]      FIG. 5  is a schematic view of an exemplary embodiment of a collection unit for collecting finished fabric from the automated process of  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     Referring to the drawings and in particular to  FIG. 1 , an exemplary embodiment of a process  10  according to the present disclosure is shown. Process  10  is effective at continuously dyeing a wide fabric  12  with a dye  14 . Fabric  12  can be a warp knit fabric in its un-dyed or raw state.  
         [0024]     Process  10  has a first station  16 , a second station  18 , and a third station  20 . Fabric  12  is, preferably, moved among the first, second, and third stations  16 ,  18 ,  20  in a machine direction  22 . Alternately, it is contemplated for stations  16 ,  18 ,  20  to move with respect to fabric  12  in a direction opposite to the machine direction  22 . Further, it is contemplated for stations  16 ,  18 ,  20  and fabric  12  to move with respect to one another.  
         [0025]     At first station  16 , folds are removed from fabric  12 . For example, first station  16  can draw fabric  12  over a former  24  so that the former ensures that the fabric is taut and, thus, any folds or creases in the fabric are substantially removed. Former  24  can be a substantially planar frame as shown in  FIG. 1 .  
         [0026]     In an alternate exemplary embodiment, process  10  draws fabric  12  from a supply of fabric, such as a knitting machine or a fabric roll  26  so that the fabric is taut and, thus, any folds or creases in the fabric are substantially removed.  
         [0027]     Next, process  10  exposes fabric  12  to second station  18  where at least one surface (e.g., technical face or technical back) of the fabric are sprayed with the dye. This is preferably achieved by controlling a spray nozzle  28  to spray fabric  12  with dye  14 . In the illustrated embodiment, nozzle  28  is a stationary or fixed nozzle that sprays fabric  12  with dye as the fabric is moved in machine direction  22 . Nozzle  28  can be a linear spray bar as shown. Of course, it is contemplated by the present disclosure for nozzle  28  to move with respect to fabric  12 .  
         [0028]     For purposes of clarity, former  24  is shown in  FIG. 1  ending before second station  18 . Preferably, first and second stations  16 ,  18  are at the same point along process  10  so that former  24  removes folds and creases from fabric  12  in the area of spray nozzle  28 . Thus, process  10  provides former  24  at least in the area of second station  18 .  
         [0029]     Process  10  then exposes fabric  12  to third station  20  before dye  14  dries on the fabric. Third station  20  spreads dye  14  throughout fabric  12  and affixes the dye to the fabric so that the dye reacts with and affixes to a component of the fabric  12 . The term “reactive” or “reacts” as used herein shall mean the action of the dye with the fabric that results in the formation of an attachment to the one or more components of the fabric, wherein the attachment can be a covalent bond, an ionic bond, a disbursement into the fiber molecule, or any combination of the foregoing.  
         [0030]     For example, the fabric  12  can be a polyamide fabric with or without an elastic yarn, including elastane, lycra, nylon, spandex, or any combinations thereof. Dye  14  can be a dye as in U.S. Pat. No. 4,786,721, U.S. Patent Application 2002/0138922A1, European Patent Application No. EP 1 275 700, and other dyes.  
         [0031]     In one embodiment, fabric  12  is a synthetic polyamide fabric and dye  14  is a water-soluble dye that reacts with and affixes to an amine site of the fabric so that the dye can bind with the fabric. The reaction of dye  14  with the amine sites of fabric  12  affixes the dye to the fabric through the formation of a covalent bond. It has been found that dye  14  provides a degree of fixation to and penetration into the individual fibers of fabric  12 . This fixation of dye  14  to fabric  12  is sufficient to allow the dye to be sprayed on only on one surface of the fabric (e.g., technical face), while providing substantially uniform color at the second surface (e.g., technical back).  
         [0032]     Fabric  12  is described above by way of example as a synthetic polyamide fabric. Additionally, dye  14  is described above by way of example reacting with an amine site of the synthetic fabric. However, it is contemplated by the present invention for fabric  12  to be made of any natural fiber, synthetic fiber, or any combination thereof. Similarly, it is contemplated by the present invention for dye  14  to be any fiber-reactive compound. For example, dye  14  can be a dye capable of reacting with and/or chemically bonding to the hydroxyl groups of cellulose fibers (e.g., cotton), the amino, carboxy, hydroxy and/or thiol groups of wool or silk fibers, and/or the amino groups and/or carboxy groups of synthetic polyamides.  
         [0033]     Third station  20  exposes fabric  12  to steam and heat in a manner and amount sufficient to spread dye  14  throughout fabric  12  and affix the dye to the fabric. For example, third station  20  can have a steam hood that exposes fabric  12  to steam and heat in a manner and amount sufficient to spread dye  14  throughout fabric  12  and affix the dye to the fabric as the fabric is continuously moved through the third station  20 . When affixing dye  14  to fabric  12  made of natural fibers, third station  20  can apply saturated steam, such as atmospheric steam (i.e., steam at atmospheric pressure) at a temperature of about 102 degrees Celsius and a relative humidity of about 100 percent. Third station  20  can apply steam to fabric  12  for about 1 to 7 minutes, preferably about 3 to 5 minutes. When affixing dye  14  to fabric  12  made of synthetic fibers and/or combinations of natural and synthetic fibers, third station  20  can apply saturated steam, such as superheated steam (i.e., steam at atmospheric pressure) at a temperature of up to about 130 degrees Celsius and a relative humidity of upto about 100 percent.  
         [0034]     After dye  14  has been spread through and affixed to fabric  12  at third station  20 , fabric  12  can be exposed to a fourth station  30 . Fourth station  30  can wash off or remove any unfixed dye  14  from fabric  12 .  
         [0035]     Advantageously, process  10 , with or without the use of former  24 , minimizes contact with fabric  12  to reduce the surface area for condensation to gather and reduce dye bounce off, allows sprayed dye to pass through the garment, minimizes the formation of condensation by on the former. Thus, process  10  also eliminates or mitigates many of the deleterious effects that can occur during spray dyeing.  
         [0036]     In some embodiments, process  10  can include a fifth station  32  positioned between second station  18  and third station  20  as shown in phantom. Fifth station  32  can include a heating device  34  for adjusting the moisture content of fabric  12  after application of dye  14  at second station  18 , but before exposure to the steam of third station  20 . For example, heating device  34  can include a radiant heating device, a convection device, or any combinations thereof.  
         [0037]     Importantly, fifth station  32  does not dry dye  14  or fabric  12 . Rather, fifth station  32  adjusts the moisture content of fabric  12 . After exposure to second station  18 , fabric  12  has a moisture content of between about 30% to about 100%, and all subranges therebetween. Preferably, fifth station  32  adjusts the moisture content of fabric  12  to between about 20% to about 80% prior to exposure to third station  20 .  
         [0038]     Without being limited to any particular theory, it is believed that the heat from fifth station  32  is sufficient to act as a catalyst to start the reaction of dye  14  with fabric  12 , which assists process  10  in yielding a fixation rate of the dye to the fabric  12  of between about 80% to about 90%. In addition, fifth station  32  may assist in preventing dye  14  from dripping from fabric  12  prior to exposure to third station  20 .  
         [0039]     Alternate exemplary embodiments of the process according to the present disclosure are shown in  FIGS. 2 and 3 , where component parts performing similar and/or analogous functions are labeled in multiples of one hundred.  
         [0040]     In the embodiment illustrated in  FIG. 2 , process  110  is shown continuously dyeing a tubular fabric  112  with dye  114 . Fabric  112  can be a circular or weft knit fabric in its un-dyed or raw state.  
         [0041]     Process  110  has a first station  116 , a second station  118 , and a third station  120 . Fabric  112  is, preferably, moved among the first, second, and third stations  116 ,  118 ,  120  in a machine direction  122 . Alternately, it is contemplated for stations  116 ,  118 ,  120  to move with respect to fabric  112  in a direction opposite to the machine direction  122 . Further, it is contemplated for stations  116 ,  118 ,  120  and fabric  112  to move with respect to one another.  
         [0042]     At first station  116 , folds are removed from fabric  112 . For example, first station  116  can draw fabric  112  over a former  124  so that the former opens the tubular fabric to knitted size width and ensures that the fabric is taut and, thus, any folds or creases in the fabric are substantially removed. Former  124  can be one or more substantially tubular frames as shown in  FIG. 2 . As used herein, the term “open” when used with respect to tubular fabric shall mean that the interior surface (e.g., the technical back) of the fabric does not contact itself.  
         [0043]     In an alternate exemplary embodiment, process  110  can draw fabric  112  from a supply of fabric, such as a roll of circular-knit fabric or a circular-knitting machine  126  so that the fabric is taut and, thus, any folds or creases in the fabric are substantially removed.  
         [0044]     Next, process  110  exposes fabric  112  to second station  118  where an exterior surface (e.g., technical face) of the fabric is sprayed with the dye. This is preferably achieved by controlling a spray nozzle  128  to spray fabric  112  with dye  114 . In the illustrated embodiment, nozzle  128  is a stationary or fixed nozzle that sprays fabric  112  with dye as the fabric is moved in machine direction  122 . Nozzle  128  can be a circular spray bar as shown. Of course, it is contemplated by the present disclosure for nozzle  128  to move with respect to fabric  112 .  
         [0045]     For purposes of clarity, former  124  is shown ending before second station  118 . Preferably, first and second stations  116 ,  118  are at the same point along process  110  so that former  124  removes folds and creases from fabric  112  in the area of spray nozzle  128 . Thus, process  110  provides former  124  at least in the area of second station  118 .  
         [0046]     Process  110  then exposes fabric  112  to third station  120  before dye  114  dries on the fabric. Third station  120  spreads dye  114  throughout fabric  112  and affixes the dye to the fabric. As discussed above, third station  120  can have a steam hood that exposes fabric  112  to steam and heat in a manner and amount sufficient to spread dye  114  throughout fabric  112  and affix the dye to the fabric as the fabric is continuously moved through the third station. When affixing dye  114  to fabric  112  made of natural fibers, third station  120  can apply saturated steam, such as atmospheric steam (i.e., steam at atmospheric pressure) at a temperature of between about 60 to about 102 degrees Celsius and a relative humidity of about 100 percent. Third station  120  can apply steam to fabric  112  for about 1 to 7 minutes, preferably about 3 to 5 minutes. When affixing dye  114  to fabric  112  made of synthetic fibers and/or combinations of natural and synthetic fibers, third station  120  can apply saturated steam, such as superheated steam at a temperature of up to about 130 degrees Celsius and a relative humidity of upto about 100 percent.  
         [0047]     After dye  114  has been spread through and affixed to fabric  112  at third station  120 , fabric  112  can be exposed to a fourth station  130 . Fourth station  130  can wash off or remove any unfixed dye  114  from fabric  112 .  
         [0048]     Advantageously, process  110 , with or without the use of former  124 , minimizes contact with fabric  112  to reduce the surface area for condensation to gather and reduce dye bounce off, allows sprayed dye to pass through the garment, minimizes the formation of condensation by on the former. Thus, process  110  also eliminates or mitigates many of the deleterious effects that can occur during spray dyeing.  
         [0049]     Process  110  can also include a fifth station  132  positioned between second station  118  and third station  120  as shown in phantom. Fifth station  132  can include one or more heating devices  134  (only one shown) for adjusting the moisture content of fabric  112  after application of dye  114  at second station  118 , but before exposure to the steam of third station  120 . For example, heating device  134  can include a radiant heating device, a convection device, or any combinations thereof. Preferably, process  110  includes both a plurality of heating devices  134  configured to generate a curtain of hot air (not shown) through which fabric  112  moves. In some embodiments, the curtain of hot air can assist in transporting fabric  112  into third station  120 .  
         [0050]     Importantly, fifth station  132  does not dry dye  114  or fabric  112 . Rather, fifth station  132  adjusts the moisture content of fabric  112 . After exposure to second station  118 , fabric  112  has a moisture content of between about 30% to about 100%. Preferably, fifth station  132  adjusts the moisture content of fabric  112  to between about 20% to about 80% prior to exposure to third station  120 .  
         [0051]     In the embodiment illustrated in  FIG. 3 , process  210  is shown continuously dyeing a tubular fabric  212  with dye  214 . Fabric  212  can be a circular or weft knit fabric in its un-dyed or raw state.  
         [0052]     Process  210  has a first station  216 , a second station  218 , a third station  220 , a fourth station  230 , and, if needed, a fifth station  232 . Fabric  212  is, preferably, moved among the stations in a machine direction  222 . Alternately, it is contemplated for the stations to move with respect to fabric  212  in a direction opposite to the machine direction  222 . Further, it is contemplated for the stations and the fabric  212  to move with respect to one another.  
         [0053]     At first station  216 , fabric  212  is opened and folds or creases are removed from the fabric. For example, first station  216  can draw fabric  112  from a supply of fabric  226  through an air bearing opening unit  224 , known in the art, the former opens the tubular fabric and ensures that the fabric is taut and, thus, any folds or creases in the fabric are substantially removed. Advantageously, air bearing unit  224  maintains fabric  212  in the open state as the fabric moves through second station  218  and, when present, fifth station  232 .  
         [0054]     Second station  218  sprays one or more exterior surfaces  236  (e.g., technical face) of the open fabric with dye  214  as shown in  FIG. 4 . This is preferably achieved by controlling one or more spray nozzles  228  (only two shown) to spray the fabric  212  with dye  214 . Preferably, nozzle  228  moves in a direction  238  that is perpendicular to machine direction  222 .  
         [0055]     In some embodiments, process  210  includes fifth station  232  positioned between second station  218  and third station  220 . Fifth station  232  can include a heating device  234  for adjusting the moisture content of fabric  212  after application of dye  214  at second station  118 , but before exposure to the steam of third station  220 . Importantly, fifth station  212  does not dry dye  214  or fabric  212 . Rather, fifth station  232  adjusts the moisture content of fabric  212  to a desired range. Preferably, fifth station  232  adjusts the moisture content of fabric  212  to between about 20% to about 80% prior to exposure to third station  220 .  
         [0056]     Third station  220  exposes fabric  212  to atmospheric steam (i.e., steam at atmospheric pressure) before dye  214  dries on the fabric. As discussed above, third station  220  exposes fabric  212  to steam and heat in a manner and amount sufficient to spread dye  214  throughout fabric  212  (e.g., from the technical face to the technical back) and affix the dye to the fabric as the fabric is continuously moved through the third station.  
         [0057]     Preferably, process  210  closes fabric tube  212  while maintaining the fabric taut before entry into third station  220  by, for example, running the fabric through a set of nip rollers  240 .  
         [0058]     In some embodiments, third station  220  can increase the dwell time of fabric  212  within the third station, while decreasing the size of the third station by routing the fabric through a series of vertically arranged rollers  242 . Of course, it is contemplated by the present disclosure for rollers  242  to be horizontally arranged, angled with respect to the horizontal or vertical, or any combinations thereof. It is also contemplated to adjust the speed of rollers  242  with respect to one another so that fabric  212  relaxes as it moved through third station  220 . Advantageously, the rollers  242  are configured to minimize the contact between fabric  212  and third station  220  during the fixation process.  
         [0059]     After dye  214  has been spread through and affixed to fabric  212  at third station  220 , process  210  exposes fabric  212  to a fourth station  230  to wash off or remove any unfixed dye from the fabric. Fourth station  230  returns fabric  212  to the open state using a second air bearing opening unit  224  and exposes fabric  212  to a first rinse unit  244 .  
         [0060]     First rinse unit  244  rinses the open fabric tube  212  with pressurized hot water having a temperature of between about 40 to about 80 degrees Celsius, with about 70 degrees Celsius being preferred. The use of pressurized hot water ensures the minimal use of water. In addition, it is believed that the pressure of the hot water can assist in reducing shrinkage of fabric  212  by bulking the fabric during the rinse.  
         [0061]     Next, fourth station  230  closes the fabric tube  212  by running the fabric through a second set of nip rollers  240  to extract the rinse water and unattached dye from the fabric. In some embodiments, fourth station  230  can expose fabric  212  to a second rinse unit  246  that rinses fabric  212  with pressurized hot rinse water having a temperature of between about 40 to about 80 degrees Celsius, with about 70 degrees Celsius being preferred.  
         [0062]     In some embodiments, fourth station  230  can also include a pH adjustment device. For example, first rinse unit  244  and/or second rinse unit  246  can spray rinse water having a predetermined pH level so that the rinse water adjusts the pH of the dyed fabric to a pH that is neutral and/or slightly acidic.  
         [0063]     In other embodiments, fourth station  230  can also be used to apply finishing components to fabric  212 . For example, first rinse unit  244  and/or second rinse unit  246  can spray rinse water having a finishing component, such as the aforementioned pH adjusting component, a fabric softener, a fragrance, a stain repellant component, a water repellant component, any other fabric finishing component, and any combinations thereof.  
         [0064]     Finally, fourth station  230  extracts the rinse water and unattached dye from the fabric by running the fabric through a third set of nip rollers  240 .  
         [0065]     Process  210  can then collect the finished fabric  212  at a collection unit  248 . An exemplary embodiment of a collection unit  248  according to the present disclosure is described with reference to  FIG. 5 . Collection unit  248  includes opening unit  224 , a steam box  250 , an inclined relaxing conveyor  252 , a platter  254 , and a fabric buggy  256 .  
         [0066]     Fabric  212  exiting second rinse unit  246  is opened by opening unit  224  and travels through steam box  50 . Steam box  50  adjusts the moisture level of fabric  212  to between about 70% to about 80%. Without being limited to any particular theory, it is believed that the steam and moisture from steam box  250  is sufficient to insure the relaxation of fabric  212  prior to drying for purposes of controlling shrinkage of the fabric during drying.  
         [0067]     Collection unit  248  then deposits fabric  212  on inclined relaxing conveyor  252  in a tensionless state. Fabric  212  exits conveyor  252  via platter  254  into buggy  256 .  
         [0068]     Advantageously, the processes  10 ,  110 ,  210  according to the present disclosure are continuous processes that expose the fabric to atmospheric steam without the need for expensive closed steaming chambers and without the need from a drying step before steaming. Accordingly, the processes according to the present disclosure can dye the fabric at a rate as high as about 50 yards per minute, preferably between about 3 yards per minute and about 30 yards per minute, more preferably about 20 yards per minute, and any subranges therebetween.  
         [0069]     It should be noted that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated.  
         [0070]     While the present invention has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present invention not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this invention, but that this invention will include all embodiments falling within the scope of the present disclosure.

Technology Classification (CPC): 3