Dyeing& Sizing

Dyeing is the process to color the yarn or fabric. On the other hand sizing is the process to coat the warp yarn with protective shields. Sizing is done to facilitate weaving.
Here sheet dyeing / Slasher dyeing process is used to dye the warp yarns. It is a continuous dyeing process. As the dye creates a coat on the surface of the yarn, so it is also called ring dyeing.

Machine Description of Dyeing & Sizing Machine:

a. Pre beam creel zone.
b. Sewing section
c. Ben link zone / yarn welding area
d. Accumulator BL ( Ben link) (80 mtr capacity)
e. Pre-wetting zone (for regular blue & blue black. Temperature is 70°C) or
Mercerizing Tank (for regular black temperature is 80°C) or
Pre-dyeing bath (for dark blue)
f. Two washing bath (pure soft water in room temperature is used)
g. Four dye bath
h. Three wash bath (30°C & pH is controlled)
i. Pre-drying cylinder.
j. Accumulator TA
k. Size bath / Sow box
l. Post drying cylinder
m. Accumulator BN
n. After waxing device
o. Yarn leasing area
p. Weavers beam winder

? ‘Yarn spreader roller’ is used in different places to spread the yarns properly through the process.

Some other assisting areas in the dyeing and sizing process are-
o skying zone
o dye kitchen
o size kitchen
o blower
o reserves tank
o size cooker
o beam crane
o yarn sheet spreader roller

Different portion and their model:

Machine Portion Model Name
Creeling and linking Ben link
Dyeing Ben indigo
Sizing Ben size tech
Dye kitchen Ben dye mix
Total machine Benninger Zeel

Machine Specification:

Subject Old New
Brand name Benninger Zell
Dyeing & Sizing machine Benninger Zell
Dyeing & Sizing machine
Model Ben Indigo Ben Indigo
Manufacturer Benninger Zell GMBH Benninger Zell GMBH
Year of construction 1998 2004
Country of origin Germany Germany
Creel capacity 14 14+2
Speed of winding 1-50 m/min (5-40 m/min in practical) 1-50 m/min
Warping width 1800 mm 1800 mm
Maximum reed space 2600 mm 2600 mm
Maximum beam diameter 1000 mm 1000 mm
Number of dye bath 4 6
Total no. of boxes 10 12+2
No. of dryer 10 8
No. of post dryer 14
Air pressure required 6-8 bar 6-8 bar
Air consumption 15 m----3/hr 15 m3/hr
Steam pressure required 6 bar 6 bar
Steam consumption 5500 kg/hr 5700 kg/hr
Water pressure required 2 bar 2 bar
Water consumption 20 m----3/hr 20m----3/hr
Electric power consumption 120 kW/hr 190 kW/hr
Production/day 40000 mtr/day 40000 mtr/day

? Dyeing process of Denim:

Objects:
? To get the desired color and shade.

Dyestuff used:
Generally two types of dyestuff are used to produce the desired shades. As-
a. Indigo dye
b. Sulphur Black Dye

Indigo Dye:
Type: Vat Dye
Raw material used to produce Indigo: Aniline, Fe2SO4, Monochloro acetic acid.
Manufacturing Procedure: two stages are generally required to produce indigo dye-
a. Reaction and b. finishing.

A. Reaction

Process stage Chemicals Intermediate product
Condensation Aniline, fe2so4, Monochloro acetic acid Phenyl glycerin
Ferrous (? ) salt
Potassium hydroxide Phenyl glycine
Potassium salt
Fusion & Oxidation Sodium amid potassium
Hydroxide sodium
hydroxide Indoxyl
Air Indigo press cake A
Purification Acid Indigo press cake B

B. Finishing

Process stage Chemicals Intermediates & products
Fluidizing & Standardization Crude Press cake Standardized liquid
Dyeing Indigo BS GRAIN
Indigo AF POWDER

As indigo is type of vat dye, it is insoluble in water. So to make it water soluble reducing agent is used. Sodium hydro sulphite (Na2SO4) is used as the reducing agent in case of indigo dye. It is named Hydrose in the trade market.