Closed-loop textile dyeing process utilizing real-time metered dosing of dyes and chemicals

A process for dyeing a fibrous article with at least two dyes comprising:

• (a) immersing said article in a suitably heated liquid bath of a solvent medium for said dyes, said liquid bath having a predetermined alkaline pH;
• (b) adding acid to said dyeing bath during dyeing to reduce the pH according to a predetermined profile that is responsive to real-time measurements of dyeing bath pH;
• (c) adding said dyes to said dyeing bath during dyeing as liquid concentrates in a variable manner that is responsive to real-time calculations of dye uptake of each of said dyes by said fibrous article, said adding of said dyes occurring independently of said adding of said acid;
• (d) determining in real-time during dyeing (1) the solution concentration of each of said dyes in said dyeing bath and (2) the amount of each of said dyes added to said dyeing bath, and calculating the uptake of each of said dyes by said fibrous article from (1) and (2);
• (e) adjusting the rate of addition of said dyes to said dyeing bath during dyeing in accordance with said real-time calculated uptake of said dyes by said fibrous article to maintain a predetermined desired ratio of said dyes on said fibrous article during the dyeing process, wherein said adjustment of the rate of addition of said dye is made according to a predetermined exhaustion profile;
• and
• (f) controlling said dye uptake by said fibrous article from said dyebath such that said dye uptake follows said predetermined exhaustion profile, whereby said dyeing of said fibrous article is accomplished.

A process of dyeing a fibrous nylon article with at least two acid dyes comprising:

• (a) immersing said article in a suitably heated liquid bath of a solvent medium for said dyes, said liquid bath having a predetermined alkaline pH of about 8.0;
• (b) adding acid to said dyeing bath during dyeing to reduce the pH to about 5.0 according to a predetermined profile that is responsive to real-time measurements of dyeing bath pH;
• (c) adding said acid dyes to said dyeing bath during dyeing as liquid concentrates in a variable manner that is responsive to real-time calculations of dye uptake of each of said dyes by said fibrous article, said adding of said dyes occurring independently of said adding of said acid;
• (d) determining in real-time during dyeing (1) the solution concentration of each of said dyes in said dyeing bath and (2) the amount of each of said dyes added to said dyeing bath, calculating the uptake of each of said dyes by said fibrous article from (1) and (2), and comparing the ratio of the calculated uptake of said dyes to a desired ratio of said dyes on said fibrous article;
• (e) adjusting the rate of addition of said dyes to said dyeing bath during dyeing in accordance with said real-time calculated uptake of said dyes by said fibrous article to maintain a predetermined desired ratio of said dyes on said fibrous article during the dyeing process, wherein said adjustment of the rate of addition of said dye is made according to a predetermined exhaustion profile;
• and
• (f) controlling said dye uptake by said fibrous article from said dyebath such that said dye uptake follows said predetermined exhaustion profile, whereby said dyeing of said fibrous article is accomplished.

A process for dyeing a fibrous article with at least one dye comprising:

• (a) immersing said article in a suitably heated liquid bath of a solvent medium for said dye, said liquid bath having a predetermined pH;
• (b) adding acid to said dyeing bath during dyeing to reduce the pH according to a predetermined profile that is responsive to real-time measurements of dyeing bath pH;
• (c) adding said dye to said dyeing bath during dyeing as a liquid concentrate in a variable manner that is responsive to real-time calculations of dye uptake by said fibrous article, said adding of said dye occurring independently of said adding of said acid;
• (d) determining in real-time during dyeing (1) the solution concentration of said dye in said dyeing bath and (2) the amount of said dye added to said dyeing bath, and calculating the dye uptake by said fibrous article from (1) and (2);
• (e) adjusting the rate of addition of said dye to said dyeing bath during dyeing in accordance with said real-time calculated dye uptake by said fibrous article, wherein said adjustment of the rate of addition of said dye is made according to a predetermined exhaustion profile;
• and
• (f) controlling said dye uptake by said fibrous article from said dyebath such that said dye uptake follows said predetermined exhaustion profile, whereby said dyeing of said fibrous article is accomplished.