Abstract:
A rinsing station for removing residual materials from a fabric being dyed or bleached. The rinsing station includes a first pair of rinse spray nozzles. One of the first pair directed to spray a rinse fluid downwardly onto incoming dyed fabric. The other of the first pair directed to spray the rinse fluid upwardly onto the incoming dyed fabric. The rinsing station also includes a pair of nip rollers downstream for the first pair of rinse spray nozzles for extracting the rinse fluid.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/371,812, filed Feb. 16, 2009, which is a continuation-in-part of U.S. patent application Ser. No. 11/395,848, filed Mar. 31, 2006, now U.S. Pat. No. 7,799,097, which is a continuation-in-part of U.S. patent application Ser. No. 10/601,820, filed Jun. 23, 2003, now U.S. Pat. No. 7,033,403, the contents of all of which are incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is related to fabric coloring. More particularly, the present invention is related to a system and method for spray dyeing and/or bleaching fabrics. 
       BACKGROUND OF THE INVENTION 
       [0003]    Today, fabrics are made from a wide variety of natural fibers, such as cotton, synthetic fibers, and combinations thereof. The basic fabric is a greige fabric that must be dyed and/or bleached in order to provide the desired color to the resultant fabric and/or garment. Many dye compositions and methods have been proposed for dyeing fabrics; however, dyeing greige fabric remains costly in terms of materials, labor, and/or processing time. 
         [0004]    One conventional dyeing method, known as yarn dyeing, involves dyeing individual fibers or yarns prior to the fibers or yarns being sewn, knitted, or woven into a fabric. A significant problem associated with this method is the substantial inventory requirement to maintain a supply of the various colored yarns needed to produce various products, and the prohibitively high inventory costs resulting therefrom. 
         [0005]    Another conventional dyeing method is known as bulk dyeing. In bulk dyeing, un-dyed fibers or yarns are knitted or woven into a raw or undyed fabric. The raw fabric is subsequently scoured or bleached, and then dyed. 
         [0006]    Common bulk dyeing methods 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 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 in a rotating drum. 
         [0007]    There are a number of problems, however, associated with bulk dyeing methods. First, the bulk dyeing process necessitates large volumes of water, which increases the costs of the bulk dyed fabrics, and has an adverse impact on the environment and conservation of natural resources. Also, some of the dyed fabric must be cut away from templates during the manufacture of a garment from the fabric. Since the bulk fabric has already been dyed, this results in increased costs due to the wasted dye and fabric. 
         [0008]    A more significant problem with bulk dyed fabrics in the manufacture of garments is the unpredictability of consumer color preferences. In the garment industry, changes in consumers&#39; preferences for one color over another color can lead to an overstock of the undesired colored garments and a back-order of the desired colored garments. 
         [0009]    Other methods of dyeing fabrics involve printing dyes onto a surface of a fabric. These methods are commonly used to apply a decorative pattern on the surface of the fabric. Such printing methods include screen-printing and inkjet printing. While these methods have proven useful in quickly changing from one decorative pattern to another, they have not proven useful for large scale production of fabrics or garments. 
         [0010]    Accordingly, there is a continuing need for flexible, low cost, low waste processes for dyeing fabrics. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic view of an exemplary embodiment of the system for dyeing and/or bleaching fabric according to the present invention. 
           [0012]      FIG. 2  is a perspective view of the ring guides and the scroll roll of the exemplary embodiment of the system of  FIG. 1 . 
           [0013]      FIG. 3  is a schematic view of the spray dyeing station of the present invention. 
           [0014]      FIG. 4  is a schematic view of the rinsing stations of the present invention. 
           [0015]      FIG. 5  is a schematic view of the collection unit of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring to the figures in general, and to  FIG. 1 , in particular, one aspect of the present invention is directed to a system, shown generally as reference numeral  100 , for continuously dyeing a fabric. Another aspect of the present invention, as described herein, is the method for continuously dyeing a fabric with reference to the system. 
         [0017]    In one exemplary embodiment, the system  100  comprises a fabric positioning station  110 , a spray station  120 , a fixation station  150 , and at least one rinse station  160 . As described in greater detail below, the system  100  may further comprise a drying unit  180  or a fabric handling station  190  (shown in  FIG. 4 ). Shown generally as reference numeral  14 , the fabric  14  may be a tubular knit fabric in its un-dyed or raw (greige) state, although the invention is not limited to dyeing tubular knit fabric. Indeed, any fabric substrate can be dyed using the system and method of the present invention. 
         [0018]    In one exemplary embodiment, fabric  14  is drawn from a supply of fabric, such as a knitting machine or fabric roll  12  by a downstream roller  117 , as described in greater detail below. As shown in  FIG. 1 , at the fabric positioning station  110 , folds are removed from the fabric  14 . For example, the fabric  14  may be drawn through opposed ring guides  112 , on either side of the flat fabric  14 , over a spreader bar  114 , or former, that opens the tubular fabric  14 . As shown in  FIG. 2 , the ring guides each comprise a pair of balls, which rotate about a vertical axis to engage and hold the fabric  14  taut. The spreader  114  ensures that the fabric is flat and, thus, any folds or creases in the fabric are substantially removed. 
         [0019]    After passing over the spreader  114  and through the ring guides  112 , the fabric is allowed to relax as it passes beneath roller  115 , which serves to maintain the appropriate tension on the fabric and guide the fabric to a driven scroll roll  117 . As best shown in  FIG. 2 , the scroll roll  117  is a roller having a rubber outer coating with angled, raised ribs  117   a , which diverge outwardly from the center of the roller toward the opposed ends  117   b  of the scroll roll  117 . As the scroll roll  117  rotates, drawing the fabric  14  across the top of the roller  117 , the ribs pull the fabric outwardly to keep it taught and smooth. 
         [0020]    The fabric  14  is next drawn through the spray station  120  by downstream rollers  154 , where at least one surface, i.e., the technical face or technical back, of the fabric is sprayed with dye. As illustrated schematically in  FIG. 1 , in one embodiment the spray station  120  comprises upper and lower portions  120   a  and  120   b,  for spraying both technical faces of the flat tubular fabric  14 . Referring to  FIG. 3 , the spray station  120  is shown in greater detail. A vessel  121  holds the desired volume of a dye composition, such as a reactive dye mixture. The terms “reactive” or “reacts,” as used herein, refer to the reaction of the dye with the fabric that results in the formation of an attachment to one or more components of the fabric, such as by a covalent bond. Suitable reactive dye compositions are described in U.S. Pat. No. 4,786,721 and in pending U.S. patent application Ser. Nos. 11/338,346, 11/656,769, and 12/329,684, which are incorporated herein by reference. The present invention reduces the amount of water required for dyeing the fabric. Specifically, whereas conventional dyeing processes require about a 6:1 ratio of water to dye, the system and method of the present invention require only about a 1:6 ratio of water to dye. 
         [0021]    The dye composition is drawn from the vessel  121  by fluid pumps  122 . As shown in  FIG. 3 , where the spray station comprises upper and lower portions  120   a  and  120   b,  the system  100  comprises two parallel paths and two fluid pumps  122   a,    122   b  in parallel. To regulate the volume of dye composition sprayed onto the faces of the fabric  14 , the dye composition is pumped through flow meters  123   a,    123   b,  which are selectively set for the particular fabric type and construction, as well as the type and composition of the dye composition. The dye composition next moves through pressure regulators  124   a,    124   b  where the pressure of the spray also is selectively set, depending upon the width of the fabric and the percentage of wet pickup needed for penetration of the dye. In one exemplary operation, the pressure of the spray is about 40 pounds per square inch. Lastly, the dye composition is delivered to manifolds  126   a,    126   b,  each manifold  126  being in fluid communication with a plurality of spray nozzle heads  127   a,    127   b.  In the embodiment shown in  FIG. 3 , each manifold  126  has three spray nozzle heads  127 ; however, the actual number of spray nozzle heads is dependent upon factors that include width of the fabric being sprayed. 
         [0022]    The spray nozzle heads  127  apply the dye composition to the top and bottom surfaces, i.e., technical faces, of the open fabric  14  with dye. In one exemplary embodiment, the spray nozzles are arranged to deliver the dye composition to cover an angle of  110  degrees or less, as measured from the center of the manifolds  126   a,    126   b.  As will be appreciated, this coverage is dependent upon the width of the fabric and the distance between the spray nozzles  127  and the face of the fabric  14 . More particularly, the spray nozzles are arranged so that the dye is applied up to, but not beyond, the edges of the fabric, such that there is no overspraying of the fabric and no wastage of dye. This permits the dye to migrate around the edges of the fabric and through the fabric. Additionally, the spray nozzles are configured so that the dye composition is sprayed evenly across the width of the fabric. Further, the spray nozzles are sized, and the settings of the flow meters  123  and pressure regulators  124  selected to achieve between about 65 percent and 85 percent saturation of the total fabric, i.e., the percentage of the maximum amount that the fabric can hold. 
         [0023]    The fabric positioning station  110  and the spray station  120  described herein are equally effective in applying a bleach composition to the fabric  14 . For bleaching applications, the system may be configured so that the bleach composition and optical brighteners are mixed at the spray nozzles  127  via a separate fluid line (not shown). A suitable bleach composition is described in pending U.S. patent application Ser. No. 12/329,680, also incorporated herein by reference. The particular fabric construction and the constituents of the bleach composition will determine the extent to which the remaining portions of the system  100  described herein may be employed to treat the bleached fabric; however, it is contemplated that the system may be used to further treat the bleached fabric, such as applying softeners, stain releases, wicking agents, etc. 
         [0024]    In some embodiments of the present invention, the system further comprises one or more heating devices  130  positioned between the spray station  120  and the downstream fixation station  150 . The heating devices are set to initiate the chemical reaction of the dye. 
         [0025]    The dyed fabric  14  is next drawn over a guide roller  129  and through the fixation station  150  by rollers  154   a,  where the dyed fabric  14  is exposed to atmospheric steam, i.e., steam at atmospheric pressure, before the dye dries on the fabric. As discussed above, the color fixation station  150  exposes the fabric  14  to steam and heat in a manner and amount sufficient to spread the dye throughout the fabric, i.e., from the technical face to the technical back, and affix the dye to the fabric as the fabric is continuously moved through the station  150 . As shown in  FIG. 1 , the color fixation station  150  comprises a steam box  152 , and a plurality of rollers  154   a,    154   b  for transporting the fabric through the steam box  152  in a lengthy path, exposing both technical faces of the fabric to similar conditions. In one embodiment, only the uppermost rollers  154   a  are driven. More particularly, steam entering the steam box maintains the exposure temperature in the steam box  152  at between about 196 degrees Fahrenheit and 210 degrees Fahrenheit, and at a relative humidity of between about 60 percent and 90 percent. In one embodiment, the arrangement and rotational speed of the rollers  164  creates a path through the steam box of about nine yards (27 feet) and a dwell time within the steam box  152  of between about three minutes and four minutes. While  FIG. 1  schematically shows five rollers  154   a,    154   b,  the number of rollers may be increased or decreased depending upon the desired amount of exposure of the fabric  14  to the steam. 
         [0026]    Of course, it is contemplated by the present disclosure for rollers  154  to be horizontally arranged, angled with respect to the horizontal or vertical, or combinations thereof. It is also contemplated to adjust the speed of rollers  154  with respect to one another so that the fabric  14  relaxes as it moves through the fixation station  150 . Advantageously, the rollers  154  are configured to minimize surface contact with the fabric  14  during the fixation process. 
         [0027]    Following fixation of the dye in the fixation station  150 , the dyed fabric is advanced through ring guides  153  into at least one rinse station. Again, the ring guides  153  hold the fabric taut as it advances into the first rinse station. As shown in  FIG. 1 , in one embodiment there are two stations provided, shown as  160  and  170 , respectively. The fabric also may be overfed into the first rinse station  160  to reduce residual stresses in the fabric. 
         [0028]    Turning to  FIG. 4 , the rinse stations  160  and  170  are shown in greater detail. Upon passing into the first rinse station  160 , the fabric  14  is sprayed with pressurized hot water having a temperature of between about 100 degrees Fahrenheit and 180 degrees Fahrenheit, with about 160 degrees Fahrenheit being preferred. The use of pressurized hot water ensures the minimal use of water in the rinse process. Upon entering the first rinse station  160 , the fabric is drawn through ring guides  163  by downstream nip rollers  167  before spray nozzles  161  and  163  direct a pressurized spray vertically upward and vertically downward against the fabric. The spray action of these nozzles serves two functions. First, the vertical action of the pressurized spray cleans the dyed fabric, removing any unaffixed hydrolyzed dye, residual chemicals, and insolubles from the fabric  14 . Second, the pressurized action of the vertically directed nozzles serves to compact the tubular knitted fabric  14 . As the fabric approaches a first set of nip rollers  167 , two additional spray nozzles  165  are directed angularly upward and angularly downward toward the entrance to the nip rollers  167  to further clean and to further compact the tubular knitted fabric by the mechanical action of pushing the knitted loops (courses) of the fabric  14  against the nip rollers  167 . This effectively reduces the subsequent residual shrinkage in the fabric and apparel formed therefrom. 
         [0029]    Each of the nozzles  161  and  165  deliver about 2.6 gallons of fluid per minute at a pressure of about 1,800 pounds per square inch, for a spray volume of about six gallons per linear yard of fabric  14 . The cleaning fluid mixture comprises water at a temperature of about 160 degrees Fahrenheit, and a neutralizing agent. One suitable neutralizing agent is acetic acid. If the fabric is being bleached instead of being dyed, a peroxide scavenger is also added to the mixture. Upon passing through the first set of nip rollers  167 , about 60 percent of the excess rinse water and chemical mixture is extracted from the fabric  14 . In addition to substantially reducing the volume of water required for the cleaning and treatment at the first rinse station  160 , the resulting extracted hydrolyzed dye and liquid are not environmentally harmful. 
         [0030]    After passing through the nip rollers  167 , the fabric is drawn through ring guides  173  by downstream nip rollers  177  where two spray nozzles  175 , angled in the same fashion as the angled spray nozzles  165 , further compact the fabric  14  as it enters the second set of nip rollers  177 . The nozzles also may apply a finish such as a softener and water composition. Spray nozzles  175  also deliver about 2.6 gallons per minute at a pressure of about 1,200 pounds per square inch, for a total volume of about six gallons per linear yard. Upon passing through the nip rollers  177 , approximately 60 percent of the excess rinse water and softener finish is extracted. 
         [0031]    In some embodiments, one or more of the rinse stations may provide a pH adjustment. Alternatively, the system  100  may comprise a third rinse station  180 , shown in  FIG. 4 , wherein the rinse water has a predetermined pH level so that the rinse water adjusts the pH of the dyed fabric to a pH that is neutral or slightly acidic. Any of the rinse stations may further deliver a fragrance, a stain repellant component, a water repellant component, etc. Additionally, the first set of nip rollers  167  and second set of nip rollers  177  may have differential rotational speeds; i.e., the speed of the first set  167  may be greater than the speed of the second set  177 , thus overfeeding to the second set  179  to further facilitate compaction. The pressure applied by the nip rollers  167 ,  177  sets the moisture level remaining in the fabric  14  to between about 20 percent and 60 percent saturation. 
         [0032]    In one embodiment, the system  100  of the present invention is configured to recirculate rinse water from the rinse stations to further reduce the amount of water consumed during the dyeing and finishing of the fabric  14 . As will be appreciated by those in the art, the rinse water collected in the rinse station basis of the most downstream rinse station will be the cleanest, as it will contain the least hydrolyzed dye, chemicals, and/or insolubles. Thus, as shown by the arrows, W, collected rinse water from rinse station  180  is recirculated to the spray nozzles  175  in the second rinse station  170 . Similarly, the collected rinse water from the second rinse station  170  is recirculated to the spray nozzles  165  in the first rinse station  160 . Finally, the rinse water from the first rinse station  160  is drained or pumped for wastewater disposal. 
         [0033]    Upon exiting the second rinse station  170 , or third rinse station  180 , if included in the system configuration, the system and process may comprise a collection unit  190  for the finished, wet fabric  14 . An exemplary embodiment of a collection unit  190  according to the present disclosure is shown in  FIG. 5 . The collection unit  190  includes an opening unit  191 , an inclined relaxing conveyor  195  a platter  196  and a fabric receptacle  198 . 
         [0034]    As shown in  FIG. 5 , as the fabric  14  exits the second rinse station  180 , it is opened by the opening unit  191 . The fabric is engaged by a final set of edge drives  193 , which set the width of the fabric for the subsequent collection and drying. The fabric  14  is then deposited onto the inclined relaxing conveyor  195  in a tensionless state. The fabric  14  exits the conveyor  195  via the platter  195  and is collected in the fabric receptacle  198 . 
         [0035]    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.