Abstract:
Embodiments of the present invention provide methods for achieving a pigment dye look and articles produced by same. In some embodiments, a method of dying knit fabrics includes treating a knit fabric with a cationic agent to add a positive charge to the knit fabric; and contacting the treated knit fabric with a negatively charged direct dye, wherein the direct dye adherence to the knit fabric is improved, with more uniform coloring and improved transfer resistance, while minimizing dye over-penetration, with reduced direct dye usage. In some embodiments, the method may further include cutting and sewing the dyed knit fabric to form a garment; and washing down the cut and sewn dyed knit fabric to produce a garment.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/824,926 filed Sep. 8, 2006, which is hereby incorporated by reference. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the present invention generally relate to methods for achieving a pigment dye look. More specifically the present invention relates to methods for achieving a pigment dye look without the use of pigments or formaldehyde in fabric dye form. 
         [0004]    2. Description of the Related Art 
         [0005]    Methods for dyeing knit fabrics—or more specifically, processes for producing “distressed”, “laundered”, or “vintage” looks in knit fabrics—typically do not utilize pigment dyes. Such processes using pigment dyes are not typically used in the industry because pigment dyes stain the inside of dye equipment, thus not allowing for commercially viable fabric dye with use of pigments. At present, pigment dyes for knit fabrics are done mainly in garment dye form, which is a less exact science, is more costly, and is restrictive to only garment dye facilities. 
         [0006]    Thus there is a need in the art for an improved method for producing articles having a “pigment” dye look without the use of pigment dyes. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention relates to methods for dyeing knit fabrics—or more specifically, processes for producing “distressed”, “laundered”, or “vintage” looks without the use of pigment dyes—and articles produced by same. The present invention provides the ability to achieve a “pigment dye look,” without the use of pigment, and dyed in large scale jet equipment. In the present invention, large fabric dye houses worldwide can produce fabric in their normal dye production as modified by the teachings disclosed herein, and after completion of a garment, with use of a wash down process, the desired look is achieved. 
         [0008]    In some embodiments, a method of dying knit fabrics includes treating a knit fabric with a cationic agent to add a positive charge to the knit fabric; and contacting the treated knit fabric with a negatively charged direct dye, wherein the direct dye adherence to the knit fabric is improved, with more uniform coloring and improved transfer resistance, while minimizing dye over-penetration, with reduced direct dye usage. In some embodiments, the method may further include cutting and sewing the dyed knit fabric to form a garment; and washing down the cut and sewn dyed knit fabric to produce a garment. In some embodiments an article may be provided that is produced by embodiments of the methods disclosed herein. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    So that the manner in which the above recited features and advantages of the present invention may be attained and can be understood in detail, a more particular description of embodiments of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of the invention and are therefore not to be considered limiting of its scope, for the invention may admit to other embodiments. 
           [0010]      FIG. 1  depicts a fabric preparation process in accordance with some embodiments of the invention. 
           [0011]      FIG. 2  depicts a treatment process in accordance with some embodiments of the invention. 
           [0012]      FIG. 3  depicts a cationization process in accordance with some embodiments of the invention. 
           [0013]      FIG. 4  depicts a dye process in accordance with some embodiments of the invention. 
           [0014]      FIG. 5  depicts a dye process for dark colors in accordance with some embodiments of the invention. 
           [0015]      FIG. 6  depicts a washdown process in accordance with some embodiments of the invention. 
       
    
    
       [0016]    To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. 
       DETAILED DESCRIPTION 
       [0017]    Fabric dyed in large scale jet equipment are always subject various nuances with the equipment. Dyeing of fabrics depends on weight, rope length, water PH, circulating speed time, type of fabric, type of dyes used etc. which ordinarily experienced operators understand. The present invention modifies the process of conventional operations of dyeing when using direct dyes by adding steps prior to and after the dye portion of the entire process. 
         [0018]    In all forms of fabric jet dye equipment, the operator feeds fabric into an opening at one end of the machines. With pulleys inside the machine, the fabric is continuously run in a loop fashion, while various operations are performed, usually using “in ports” (for adding various chemicals or dyes etc), as well as a pipe for adding new water, and a drop value for discharging exhausted dyes or chemicals from the machine. 
         [0019]    One aspect of the invention is the pretreat process. All knit fabrics prior to dyeing go through a pretreat process, example: scour, de-size, and/or bleach processes to prepare fabric for dyeing by eliminating unwanted waxes, oils, paraffin, yarn dust, and the like. The present invention adds a specific chemical process along with a cationization process, which allows dyes to move onto the fabric quicker, thereby reducing dye and water consumption. At the same time, this process—using a chemical, for example in one embodiment, “The Colortex effect,” (e.g., Grandex 640), produced by Grant Industries—exhausts the dyes without total penetration, so in effect, the outside of the yarn is dyed, and not totally through. This allows for a wash down process to achieve the desired look, without the use of pigment dyes. 
         [0020]    Pretreatment with “the Colortex Effect” is accomplished by contacting the goods with the chemical; this is done by injecting the chemical, in aqueous solution at a concentration selected by the operator, into the dyeing vessel through one or more injection ports. The process is run until proper exhaustion of the chemical is achieved. 
         [0021]    Adjustments to temperature, pH, and run time are handled by skilled personnel running the machines. In one embodiment, concentration of “the Colortex Effect” chemical may vary depending on the nature of the greige goods, as well as the desired shade or color of the finished goods. In general, the concentration of the chemical ranges from about 2% to about 8% (by weight in aqueous solution). For light colors, less of the chemical is used. For darker colors, more of the chemical is used. 
         [0022]    In another embodiment, the bath is heated during pre-treatment from a starting temperature to an end temperature. The starting temperature remains constant during injection of “the Colortex Effect” chemical. Then depending on the machine, the speed at which the machine is run and the nature of the fabric, a gradual increase of heat is applied. A range of between 90 and 100 degrees Fahrenheit has been found to be effective as a starting temperature for pre-treatment of greige goods in jet machinery. The bath may then be heated, with a heat-up rate of about 3 degrees per minute. In another embodiment, the bath is heated to an end temperature of around 140-180° F. and the process continues until the desired exhaustion is achieved. Usual run time is around 30-45 minutes. 
         [0023]    Once exhaustion is accomplished, the bath is dropped, and an overflow process of cold water is added to offset the dropping bath. This will lower the temperature of the fabric, as well as impart a positive charge to the fabric. 
         [0024]    As fabric is dyed, it is then framed and rolled into rolls to be sent onto the cutting room. Goods are cut and sewn in normal fashion, using polyester or nylon thread for high speed sewing. Optionally, the thread may be directly matched to the current fabric color. 
         [0025]    Once fabric is cut and sewn into garments, the final phase is the wash down process-which will yield our desired effort. This will remove excess dye from the goods, as well as create a distressed look. A number of different wash-down processes may be used to arrive at different appearances we are trying to achieve. Known wash-down processes include the use of acid enzymes, detergents, stonewashing, phosphates, neutral enzyme etc. Neutral enzymes can be used for “softer” wash-down. Acid enzymes, detergents, and stones can be used for a more distressed look. 
         [0026]    Another way of achieving a desired wash down is to over load the machine (must be rotary equipment), and underload the water ratio. Also, adding salt or sand will allow for a much stronger wash down. Just prior to rinsing, a formaldehyde free fix is added to the bath to stabilize the color. A thorough wash down is required to neutralize enzymes. A softener may be added if required for a certain type of “hand”. 
         [0027]    The use of direct dyes saves money, as well as having a long shelf life. Also, direct dyes are formaldehyde free. They also produce a much softer hand than pigment, as direct dyes will dissolve and penetrate the roping which has occurred in the dye machines, something a pigment dye cannot do. 
         [0028]    The use of the chemical in the pretreat phase, such as “The Colortex Effect” chemical, as well as abrasion or friction in the washdown phase in common lay terms, achieves a desired effect. 
         [0029]    The inventive process is a way to create consistent looking quality knits with a weathered or “pigment dye” effect, without the use of pigments, and in jet dye form (not garment dyeing). This process is friendly to the environment as water-soluble direct dyes are used and the process is formaldehyde free. Also, with the use of direct dyes, the range of available colors is greatly expanded versus pigments or sulfurs. In addition, there is no capital expenditure on the part of a dyehouse using this process, except for certain chemicals and dyestuffs. 
         [0030]    The process described above may be summarized as a four part process: 1) Pretreat of Fabric; 2) Dye of Fabric; 3) Cut and Sew; and 4) Washdown. For example,  FIG. 1  depicts a fabric preparation process in accordance with some embodiments of the invention as discussed herein;  FIG. 2  depicts a treatment process in accordance with some embodiments of the invention as discussed herein;  FIG. 3  depicts a cationization process in accordance with some embodiments of the invention as discussed herein;  FIG. 4  depicts a dye process in accordance with some embodiments of the invention as discussed herein;  FIG. 5  depicts a dye process for dark colors in accordance with some embodiments of the invention as discussed herein; and  FIG. 6  depicts a washdown process in accordance with some embodiments of the invention as discussed herein. 
         [0031]    In the Pretreat of Fabric step, a fabric pretreat is performed using agents to desize, scour, and prebleach. In addition, a neutralization and a cationic pretreat is performed. The cationic pretreat will take neutral cotton and add a positive charge. This charge will allow the negatively charged dyes to move more quickly onto the fabric, with less salt and a lower water ratio. Moreover, the pretreat of fabric step facilitates lower consumption of dye. The pretreat agent further facilitates the washdown effect described below with respect to step four (washdown). 
         [0032]    The Dyeing of Fabric step, uses only high quality direct dyes and no reactive dyes. High quality direct dyes have excellent washfastness properties. Suitable examples of high quality direct dyes are available from, in a non-limiting example, Everlight. Some specific examples of high quality direct dyes available from Everlight include, Yellow RL Direct—Yellow 86, Orange 2 GL—Orange 39, Red BWS—Red 243, Blue 4BL—h/c 200, and the like. After dyeing of fabric, a formaldehyde free fix is utilized to facilitate handling of fabric after proper framing and rolling. 
         [0033]    In the Cut &amp; Sew step, polyester thread is used. The polyester thread facilitates sewing at high speeds with minor disruptions. The thread color may be matched exactly to the color dyed, even though in washdown fabric will be lighter, which helps to promote the look of the finished product. In some examples, a lot of top stitching, buttons, pockets, double needle, and the like, may be utilized to further promote the look of the fabric after washdown. 
         [0034]    In the Washdown step, agitation and abrasion are is utilized to “beat up” the dye job without damaging the garment. With proper speeds and abrasion, dyes which have not adhered to the cationized cotton will break away, or wash off. This facilitates achieving a desired “pigment dye look”. Conventionally, many washdown processes are too long in time, washing right past the desired look. The finished fabric or garment may desirably have color highs and lows around the seams, pockets, zippers, and the like, and not a uniform washdown of the entire garment. 
         [0035]    With the use of high quality direct dyes, a warm soap and water washdown may be utilized. For example, a washdown process may include a 40 minute warm soap and water washdown, after which the bath may be dropped, a 5 minute wash may be performed, followed by a 20 minute enzyme bath, then a fix. The inventors have discovered that most fixing agents will not pass testing. One example of a suitable fixing agent is available in Europe from Bayer, and in the United States from Starchem, under the trade name Dyeset NOZ. 
         [0036]    Thus, an improved process for Exemplary advantages of the inventive process are: 1) much larger quantity runs in piece goods versus garment dye forms; 2) better color consistency; 3) less crocking; 4) substantial savings of dyestuff versus pigment dye process; 5) use of jet dyeing equipment, as there are no pigments in this process; 6) eliminated production mistakes in the manufacturing process; 7) allows for use of polyester thread for high speed sewing; 8) achieve a nice soft hand; 9) total process is formaldehyde free. 
         [0037]    While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.