For textile coloration of cotton fabric this process is very important to know, it will help you for to acquire knowledge all about cotton knit dyeing process. All are described below...
(Here, R= Run time, T= Temperature, D= Dozing time, t= Time, min = minute). There are several steps of dyeing a batch of cotton fabrics. Those are given below:
Th batch of fabric loaded into the dyeing machine by nozzle through the wheel into the pump. The switch of wheel is on and when the whole lot is entered into the machine then both ends of fabrics are knot together. [Loading time=10m] Polly bags (3) are attached to the lot of fabrics due to facilate the cutting of sample into different stages of dyeing. Wheel speed (180) is always more than pump speed (80).
Hot wash: If the GSM of the lot of fabric is more than 180 then hot washing (T=98. R=30m) is done with Detergent & Anti-Creasing agent.
Cooling: Temperature decrease into 80. t=10-15min. Than drain
Washing: Washing is done by water(t=5min)
Drain: Waste water is drained away.
Scouring: scouring process is consists of some steps of chemical addition. At first Detergent/Wetting agent, Anti-Creasing agent, Sequestering agent, De-foaming agent are added (T=60, D=5min). Then Caustic Soda is added(T=60, D=5min) Then Peroxide is added(T=60, D=5min). Now scouring process starts. This process continues in 98 temperature for 1 hour. Then sample is cut & check until scouring is completed.
Cooling: When scouring is completed, cooling is done (T=80, t=10min).
Hot wash: Hot washing (T=80, t=10min) is done. Then normal washing is done.
Addition of peroxide killer: Peroxide killer and Acetic acid is added to remove alkaly ( it is an appearance which forms due to treating fabric with chemicals) from the fabric. Here T=90, t=10min)
pH checking: After washing the fabric, pH checking is done by pH paper with addition of Acetic acid. pH should be 4.5
Enzyme Washing: Enzyme is added for enzyme washing (T=55, t=60min). As enzyme activates at 55 temperature. Then sample is cut & check until washing is completed. After it normal washing is done.
Addition of Anticreasing agent: Addition of Antcreasing agent is done with detergent due to resistant colour crease (no crease during dyeing) in T=40, R=10min
pH checking: pH of fabric is checked by pH paper and maintain it 5.5 by addition of acetic acid in order to add leveling agent.
Addition of Leveling agent: Addition of leveling agent is done with a Little amount of Detergent. (D=10min R=10min, T=40)
Addition of salt: Salt is dosing for 30 min with Temperature 40 & R=20. If Light shade requires less salt after dye addition and deep shade requires more salt before dye addition.
Addition of Dye: Dye solution make more soluble in dye tank with hot water and addition done by dosing (D=25min, T=40). Then run for 10min. Then sample is cut for checking salt. This is called salt sample which is not washed.
Migration: If critical colour then Migration is done (T=80, t=20min) to avoid Uneven shade.
Addition of Soda Ash: Soda is dosing for 30min in t=40. Soda works for fixation of colour.
Color steam: Temperature increased to 60 and run the machine for 10min. This is dyeing process. Then sample cut & match the shade, if not match then dyeing process continues.
Color Wash: If shade is match with swatch then normal washing is done. After that washing done with Washing/Soaping agent (T=60, t=30min). This wash is called color wash. If shade is deep the washing requires more time. Washing/Soaping agent is used for remove the unfixed dye from the fabric surface. Then again hot washing is done.
Addition of Acid: Addition of Acetic acid is done to remove alkali which is created by salt & soda. Acid also remove bacteria from the surface of the fabric. Then washing is done for 20min.
Addition of Softener: Softener dosing is done for 30min and run for 10min. Then sample is cut & check. This sample is not washed. Softener is adding for make fabric soft, improve handfeel properties. Basic function of Softener is to soft the fabric. Softener enters into the polymer chain of molecules and rearranges them into new order.
Addition of Silicon: In some cases silicon is dosing (D=15min, T=40). Silicon is a chemical which is used to impart glance and silky appearance (like pitch finish) onto fabric.
Unload: After that Washing is done, unload the fabric.
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