Avoiding stains in dyed cationically modified cotton fabrics

Abstract

The present invention is a method for improving the stain resistance of a cationized fiber or textile comprising natural fiber. The method comprises the steps of immersing the cationized fiber or textile in an aqueous solution having a given pH and then contacting the fabric immersed in the aqueous solution with an acrylic polymer having a standard pH under conditions sufficient to allow at least a portion of the acrylic polymer to attach to the fiber or fabric. Notably, for long lasting staining resistance, the aqueous solution has been selected or adjusted to have a ph that is similar to the standard pH of the acrylic polymer prior to the addition of the acrylic polymer. While for short term staining resistance, the aqueous solution has been selected or adjusted to have a pH that is close to the standard pH of the acrylic polymer prior to the addition of the acrylic polymer. For short term staining resistance, if the acrylic polymer has a acid standard pH, the aqueous solution should have an acid or neutral pH; if the acrylic polymer has an alkaline pH, the aqueous solution should have an alkaline or neutral pH; And if the acrylic polymer has a neutral pH, the aqueous solution should have any acid, neutral or alkaline pHs.

1 . A method for improving the long lasting stain resistance of a cationized fiber or textile comprising natural fiber, the method comprising the steps of:
 a. immersing the cationized fiber or textile in an aqueous solution having a given pH   b. contacting the fabric immersed in the aqueous solution with an acrylic polymer having a standard pH under conditions sufficient to allow at least a portion of the acrylic polymer to attach to the fiber or fabric;   wherein the aqueous solution has been selected or adjusted to have a pH that is similar to the standard pH of the acrylic polymer prior to the addition of the acrylic polymer.   
     
     
         2 . The method of  claim 1  wherein the aqueous solution in step a. contains a softener. 
     
     
         3 . The method of  claim 1  where the aqueous solution has a pH in the range of from 4 to 10 at the time of contact with the acrylic polymer. 
     
     
         4 . The method of  claim 3  where the acrylic polymer has a pH lower than 6 and the aqueous solution has a pH in the range of 4 to 6. 
     
     
         5 . The method of  claim 3  where the acrylic polymer has a pH in the range of from 6 to 8 and the aqueous solution has a pH in the range of from 6 to 8. 
     
     
         6 . The method of  claim 3  where the acrylic polymer has a pH greater than 8 and the aqueous solution has a pH in the range of from 8 to 10. 
     
     
         7 . A method for improving the short term stain resistance of a cationized fiber or textile comprising natural fiber, the method comprising the steps of:
 a. immersing the cationized fiber or textile in an aqueous solution having a given pH with or without the presence of a softener;   b. contacting the fabric immersed in the aqueous solution with an acrylic polymer having a standard pH under conditions sufficient to allow at least a portion of the acrylic polymer to attach to the fiber or fabric;   wherein the aqueous solution has been selected or adjusted to have a pH that is close to the standard pH of the acrylic polymer prior to the addition of the acrylic polymer. If the acrylic polymer has an acid standard pH, the aqueous solution should have an acid or neutral pH; if the acrylic polymer has an alkaline pH, the aqueous solution should have an alkaline or neutral pH; And if the acrylic polymer has a neutral pH, the aqueous solution should have any acid, neutral or alkaline pHs.   
     
     
         8 . A method for improving the stain resistance of a cationized fiber or textile comprising natural fiber, the method comprising the steps of:
 a. immersing the cationized fiber or textile in an aqueous solution having a given pH;   b. contacting the fabric immersed in the aqueous solution with an acrylic polymer having a standard pH under conditions sufficient to allow at least a portion of the acrylic polymer to attach to the fiber or fabric;   wherein the aqueous solution has been selected or adjusted to have a pH that is suitable for the desired long term or short term stain resistance,   wherein for long lasting stain resistance the aqueous solution has been selected or adjusted to have a pH that is similar to the acrylic polymer's standard pH, such that where acrylic polymer has a pH lower than 6 the aqueous solution is selected or adjusted to have a pH in the range of 4 to 6, and where the acrylic polymer has a pH in the range of from 6 to 8, the aqueous solution is selected or adjusted to have a pH in the range of from 6 to 8 and where the acrylic polymer has a pH greater than 8 the aqueous solution is selected or adjusted to have a pH in the range of from 8 to 10; and   wherein for short term stain resistance the aqueous solution has been selected or adjusted to have a pH that is similar or close to the acrylic polymer's standard pH, such that where acrylic polymer has a pH lower than 6 the aqueous solution is selected or adjusted to have a pH in the range of 4 to 8, and where the acrylic polymer has a pH in the range of from 6 to 8, the aqueous solution is selected or adjusted to have a pH in the range of from 4 to 10 and where the acrylic polymer has a pH greater than 8 the aqueous solution is selected or adjusted to have a pH in the range of from 6 to 10.   
     
     
         9 . The method of  claim 8  where the acrylic polymer has a molecular weight in the range of from 2000 to 30,000 g/mol. 
     
     
         10 . The method of  claim 8  where the acrylic polymer has a molecular weight in the range of from 2,150 to 4,500 g/mol. 
     
     
         11 . The method of  claim 8  where the acrylic polymer is a homopolymer, copolymer or a terpolymer. 
     
     
         12 . The method of  claim 8  where the acrylic polymer comprises units derived from one or more monomers selected from the group consisting of acrylic acid, t-butyl acrylate and methyl methacrylate. 
     
     
         13 . The method of  claim 8  wherein the fiber or textile comprises cotton fiber. 
     
     
         14 . The method of  claim 8  wherein the fiber or textile is undyed or dyed prior to the step of contacting the fiber or textile with the aqueous solution containing the acrylic polymer. 
     
     
         15 . The method of  claim 8  wherein the fiber or textile is dyed simultaneously with the step of contacting the fiber or textile with the aqueous solution containing the acrylic polymer. 
     
     
         16 . The method of  claim 8  wherein the pH of the aqueous solution is adjusted prior to contacting the fabric with the acrylic acid by the addition of sodium hydroxide or citric acid.