Compositions and methods for dying natural fibers with natural dyes to ensure color (hue and shade)-match consistency

Abstract

This invention discloses novel and nonobvious compositions and methods suitable for the dyeing of natural fibers with natural dyes that ensure shade-match consistency.

We claim: 
     
         1 ) A process for dying yarn produced from a natural fiber using a natural dyestuff, the process comprising:
 a) providing a loosely wound yarn package having a yarn density of less than about 0.85 g/cm 3 ;   b) providing a natural dyestuff solution;   c) providing a tank that will accommodate the yarn package and an initial volume of the natural dyestuff solution;   d) providing a yarn package spectrophotometer and a natural dyestuff solution spectrophotometer;   e) contacting the yarn package and the initial volume of natural dyestuff solution within the tank under conditions appropriate for uptake of the natural dyestuff by the yarn;   f) monitoring absorbance of the yarn package by the yarn package spectrophotometer and the natural dyestuff solution by the natural dyestuff solution spectrophotometer;   g) supplementing the initial volume of natural dyestuff solution with an appropriate quantity of the natural dyestuff solution, as needed, to achieve a condition wherein the yarn package spectrophotometer detects absorbance at a desired wavelength and the natural dyestuff solution spectrophotometer detects absorbance consistent with a substantially depleted natural dyestuff solution;   h) replacing the dyestuff solution with a solution comprising ferrous sulfate at a concentration of about 1% to 8% by weight of the dry weight of goods (WOG) to be dyed; and   i) contacting the yarn package with the ferrous sulfate comprising solution for a period of time suitable to fix the dyestuff to the fibers.   
     
     
         2 ) The process of  claim 1 , wherein the yarn package is contacted with a mordant solution prior to being contacted with the dyestuff solution and wherein the mordant solution is removed before the yarn package is contacted with the dyestuff solution. 
     
     
         3 ) The process of  claim 1 , wherein the natural fiber is selected from the group consisting of wool or cotton. 
     
     
         4 ) The process of  claim 1 , wherein the natural dyestuff is selected from the group consisting logwood, cochineal, madder, cutch, myrobalan, hematine, pomegranate, and chestnut. 
     
     
         5 ) The process of  claim 1 , wherein the ferrous sulfate solution is at a concentration of about 2% to 6% by weight of the dry WOG to be dyed. 
     
     
         6 ) The process of  claim 1 , further comprising filtering the natural dyestuff solution of step b) prior to step e). 
     
     
         7 ) The process of  claim 6 , wherein the natural dyestuff solution is filtered through a 100-1000 nm filter. 
     
     
         8 ) A process for dying fabric produced from a natural fiber using a natural dyestuff, the process comprising:
 a) providing a natural dyestuff solution;   b) providing a tank that will accommodate the fabric and an initial volume of the natural dyestuff solution;   c) providing a fabric spectrophotometer and a natural dyestuff solution spectrophotometer;   d) contacting the fabric and the initial volume of natural dyestuff solution within the tank under conditions appropriate for uptake of the natural dyestuff by the yarn;   e) monitoring absorbance of the fabric by the fabric spectrophotometer and the natural dyestuff solution by the natural dyestuff solution spectrophotometer;   f) supplementing the initial volume of natural dyestuff solution with an appropriate quantity of the natural dyestuff solution, as needed, to achieve a condition wherein the fabric spectrophotometer detects absorbance at a desired wavelength and the natural dyestuff solution spectrophotometer detects absorbance consistent with a substantially depleted natural dyestuff solution;   g) replacing the dyestuff solution with a solution comprising ferrous sulfate at a concentration of about 1% to 8% by weight of the dry weight of goods (WOG) to be dyed; and   h) contacting the fabric with the ferrous sulfate comprising solution for a period of time suitable to fix the dyestuff to the fibers.   
     
     
         9 ) The process of  claim 8 , wherein the fabric is contacted with a mordant solution prior to being contacted with the dyestuff solution and wherein the mordant solution is removed before the fabric is contacted with the dyestuff solution. 
     
     
         10 ) The process of  claim 8 , wherein the natural fiber is selected from the group consisting of wool or cotton. 
     
     
         11 ) The process of  claim 8 , wherein the natural dyestuff is selected from the group consisting logwood, cochineal, madder, cutch, myrobalan, hematine, pomegranate, and chestnut. 
     
     
         12 ) The process of  claim 8 , wherein the ferrous sulfate solution is at a concentration of about 2% to 6% by weight of the dry WOG to be dyed. 
     
     
         13 ) The process of  claim 8 , further comprising filtering the natural dyestuff solution of step b) prior to step e). 
     
     
         14 ) The process of  claim 13 , wherein the natural dyestuff solution is filtered through a 100-1000 nm filter. 
     
     
         15 ) The process of  claim 8 , wherein the fabric is selected from a group consisting of woven and non-woven fabric.