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• CBIFT 141

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Cellulosic fiber

Cellulose is the main fiber that plants are made of. All plants contain cellulose. Fibers that contain cellulose include the most familiar

clothing fibers: cotton, line, rayon.

Chemical Structure of Cellulose

Types of cellulosic fiber

• Natural fibers Natural fibers are textile fibers made from plants

or animals cellulosic (from plants)Cotton (From cotton plants) flax( linen) From flax stems Jute (jute stems)

At a glancedyeing of cellulosic fiber with different

dyes

FIBER DYES

Cotton, Rayon, Hemp, Linen, Bamboo etc. Reactive dyes (mostly used)

Cotton, Rayon, Hemp, Linen Vat dyes

Cotton, Rayon, Hemp, Linen Direct dyes

Cotton, Rayon, Hemp, Linen Azo (banned)

jute Basic

Direct dyes for cellulosic fiber

• They can be dyed directly on cellulosic fiber.The effect of electrolytes to the dye liquor tends to promote exhaustion of direct dyes.

• Cellulosic fiber have a negative charge when immersed in water, electrolytes reduce the charge on the fiber surface.

Properties of direct dyes

• Soluble in water

• Anionic in nature

• Available in full range of hue

• Poor wash fastness

• Light fastness poor to fairly good

• cheap in price

Reactive dyes for cellulosic fiber

• Reactive dyes comprise of a chromophare and reactive group, they chemically react with the fiber forming covalent bonds.

Components of reactive dyes :S= solubilizing group,

C=chromophoric group,

B= bridging group,

X= reactive group.

Reactive dyes.

The three step exhaust dyeing process of reactive dyes

1. The initial exhaustion phase,

2. The fixation phase,

3. Post dyeing washing phase.

Vat dyes for cellulosic fiber

• Vat dyes are insoluble in water and can not dye fibers directly. However, they can be made soluble by reduction in alkaline solution which allows them to affix to the textile fibers

Properties of vat dyes:

1. Vat dyes are natural coloring dyes,

2. Insoluble in water,

3. Large dye stuff molecule,

4. Mostly used on cellulose,

5. Expensive in price,

6. Relatively complicated dyeing method.

Principles of application of vat dyes

A. Vatting,

B. Dyeing,

C. Oxidation,

D. After treatment.

Basic dyes

• Basic dyes are basically comes from base and the color is in the base.when acid react with base, then the color shows. As the color is in the base the dye is named basic dyes.

Properties of basic dyes

1. Brillance and intensity of color,

2. Soluble in alcohol and methylated spirit

3. Are not easily dissolved in water unless care is taken,

4. Some of them are decomposed by boiling water,

5. When treated with alkali it decomposes,

6. water containing alkali or temporary hardness should not be used,