Page 78 - Materials Chemistry, Second Edition

Ch002-P373623.qxd 3/22/07 5:27 PM Page 59
TABLE 2.24 Cleaner Production 59
Comparison Between Fabric Quality Before and After Using the Combined Process –
Misr Beida Dyers
Fabric characteristics Before (conventional After (modified
3 stage) combined)
After bleaching:
Handle Harsh Soft
Wettability (seconds) 6 2
Whiteness index 68.3 70.1
2
Tensile strength (kg/cm ) 50 52
Residual strength (%) 69.4 72.2
After dyeing:
Color uniformity Uniform Uniform
Color fastness
• Perspiration – alkaline 4 4
• Perspiration – acidic 4 4
Washing fastness 4 4

TABLE 2.25
Recipe for Combined Scour and Bleach: Knitted Fabric – Giza Spinning and Weaving
Processing recipe Combined scour and Combined scour and
(for 1 ton of fabric) half bleach full bleach
Nionil N (kg) 10 10
NaOH (47%) (l) 75 105
H 2 O 2 (50%) (kg) 30 105
Organic stabilizer (kg) 10 30
Optical brightener – Uvitex 2B (kg) – 5
Softening – Knit Soft (kg) – 30
Softening – acetic acid (11%) (kg) – 50

peroxide was used to substitute sodium hypochlorite in the full bleaching
process.
Tests were initiated on a laboratory scale winch using four standard 9 kg
samples of different fabric types (i.e. ribs, riblycra, single jersey, and inter-
lock). Using and refining the preferred laboratory scale recipe, pilot scale trials
(95 kg) and production scale trials (35–452 kg) were carried out on single jer-
sey fabric. Tests were conducted for both half and full bleach fabric. Single
jersey was used as it is the main processed fabric. Final recipes for pre-treating
1 ton of knitted fabric are summarized in Table 2.25.
Tests on fabric quality gave comparable results between the conventional
and modified combined processes as shown in Table 2.26. Subsequent dye-
ing of the modified half bleached fabric also gave acceptable depth shades.