Dyeing of cotton fabric with reactive dye (hot brand)

Theory: Reactive dye reach with fabric in presence of alkali and adheres as a part of the fiber. Three principle steps are happened during reaction dyeing. Exhaustion or reaction and after treatment as washing when a cellulosic fibre is immersed into dye solution; negative charge produce and surrounded the fiber.

On the other band the reactive dyes produce negative charge into dye both, thus a repulsion force occurred. Use of electrotypes neutralizes the negative surface charge of the fiber. Due to affinity of the reactive dye to the fiber acidity the dye molecules move forward to the surface of the fiber. Thus phase of dyeing is called absorption. Then the dye molecules diffused into the swelled fiber structure through fiber pores and distribute over the fib. This step is called exhaustion.

Recipe:

Dyes = 3%

Glober salt (Na₂SO₄) = 60 g/l

Soda (NA₂CO₃) = 20  g/l

Wetting agent = 1 g/l

Sequestering agent = 1 g/l

Levelling agent = 1 g/l

Temp = 80°C

Time = 50 min

Sample weight =5 gm

Neutralization:

CH₃COOH = 1 g/l

Temp = 50°C

Time = 10 min

Soaping:

Detergent = 1 g/l

Time = 10 min 

Temp = 95 °C

Friction of the chemical required:

Wetting agent: It accelerates the wettability of material in solution thus helps to easy penetration of chemicals into substrate.

Sequestering agent: it one kind of surfactants surface active agent act in solid liquid , solid gas or liquid gas interfaces and reduces the interfacial tension.

Levelling agent: Levelling agent is used in textile coloration process to active uniform dyeing over whole substrate by controlling the rate of dyeing.

Electrolytes: Use of electrolytes neutralizes the negative surface charge of fiber.

Recipe calculation:

Dye: 100 gm fabric for  3 gm dye

           1     gm        “     “    3/100 “

            5   gm        “   “         3×5 / 100 “ = 0.15 gm

Water: 200 gm [ m:L = 1:40]

Na₂SO₄  = 1000 CC water, NA₂CO  required = 60 gm

                    1              “              “               “      =60 / 1000 “

                    200          “                “             “      = 60 × 200 / 1000    gm = 12g

Similarity,

NA₂CO₃  = 4 g/l

Wetting agent = 0.2 g/l

Sequestering agent = 0.2 g/l

Levelling agent = 0.2 g/l

CH₃COOH = 0.2 g/l

Detergent = 0.2 g/l

Conclusion: Now-a day reactive dyes are very popular for textile coloration because of its some specific properties like color fastness wide range of shad, brilliance of shade , good reproducibility and simple application procedure.