Yaa Bleach Launder Of Woven Denims: Analysis Of Earlier As Well As Afterward Launder Properties (Part-3)

Bleach Wash of Woven Denims: Analysis of earlier together with subsequently Wash Properties (Part-3)

S.M. Bappy Rana
Dept. of Textile Engineering
People's Republic of Bangladesh University of Business & Technology
Cell: +8801781630519

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2.8 Bleach washing:
This agency endure considered every bit a preparatory procedure of mercerizing, dyeing, or printing .therefore proper bleaching should endure carried out other want the subsequent procedure would endure fault.

Objective:

To withdraw the size cloth from the garments.
To withdraw the starch introduce on the garments.
For soft feeling to vesture the garments.
To increase the color fastness together with rubbing fastness.
Especially prepare the “Bio-polishing’’ impact cotton/Denim.

2.9 Bleaching pulverisation (CaOCl2):
Bleaching pulverisation is a mixture of calcium hypochlorite, CaOCl₂ together with calcium chloride CaCl2. Thus, its chemic composition is CaOCl₂ + CaCl2 or tin endure written every bit CaOCl₂ or Ca(OCl)Cl (Calcium chloro hypochlorite).

Bleaching pulverisation is manufactured past times passing chlorine gas over dry out slaked lime at 400 C.

Ca (OH)₂ + Cl₂ ← CaOCl₂ + H₂O

Properties:
1. It is an yellowish white pulverisation amongst rigid odor of chlorine together with is soluble inwards water. Aqueous solution of bleaching pulverisation contains chloride together with hypochlorite ions.

CaOCl₂ ↔ Ca₂+ + Cl- + ClO-

2. In presence of modest quantities of dilute acids, it liberates nascent oxygen. Thus it human activity every bit oxidizing agent.

2CaOCl₂ + H ₂SO₄ → CaCl₂ + CaSO₄ + 2HClO

HClO ← HCl + [O]

3. When bleaching pulverisation is treated amongst excess of dilute acid or CO2, whole of the chlorine introduce inwards the molecules is evolved. The total chlorine together with so liberated is called available chlorine. Influenza A virus subtype H5N1 skilful sample of bleaching pulverisation contains 35-38% available chlorine.

CaCl₂ + 2HCl → CaCl₂ + H ₂O + Cl₂

CaOCl₂ + CO₂ → CaCO₃ + Cl₂

2.10 Mechanism of bleaching action:
Color inwards virtually dyes together with pigments is produced past times molecules, such every bit beta carotene, which incorporate chromophores. Chemical bleaches travel inwards i of 2 ways

An oxidizing bleach plant past times breaking the chemic bonds that brand upwardly the chromophore. This changes the molecule into a unlike core that either does non incorporate a chromophore, or contains a chromophore that does non absorb visible light.

A reducing bleach plant past times converting double bonds inwards the chromophore into unmarried bonds. This eliminates the might of the chromophore to absorb visible light.

2.11 Different type of bleaching agent:

1) Oxidizing Agent: