Characteristics of reactive group of reactive dye:
- The characteristics of reactive group of dye are mentioned below:
- Reactive groups do not contribute to the color of dye. Chromogen group imparts it.
- The reactivity of vinyl sulphone group is less than that of halogen group.
- If no of reactive group increases, binding also increases depending on dye structure.
- Reactive dye absorb up to 90%.
- Molecular weight of reactive group 69-211gm/ mole.
- Bond energy of halogen groups are as below:
F
(Fluorine)- 102-kcal/ gm
Cl
(chlorine) – 74-kcal/ gm
I (iodine)
- 56-kcal/ gm
- If the molecular weight of reactive group increases, reactivity also increases.
- Reactivity of iodine is high but tits rate of hydrolysis is also high.
- Chlorine imparts medium reactivity, but it is cheap and hydrolysis rate is medium.
- Reactivity of fluorine is the least and its rate hydrolysis is also less.
- Reactivity of vinyl sulphone group increases with increasing temperature and pH.
- Sulphone group has more solubility but it is not stable.
- Generally low molecular weight dyes are of hot brand.
- Less affinity dyes are used for pad method.
Properties
of reactive dye:
- Reactive dyes are cationic dyes, which are used for dyeing cellulose, protein and polyamide fibres.
- Reactive dyes are found in power, liquid and print paste form.
- During dyeing the reactive group of this dye forms covalent bond with fibre polymer and becomes an integral parts of the fibre.
- Reactive dyes are soluble in water.
- They have very good light fastness with rating about 6. The dyes have very stable electron arrangement and can protect the degrading effect of ultra-violet ray.
- Textile materials dyed with reactive dyes have very good wash fastness with rating about 4-5 due to strong covalent bonds formed between fibre polymer and reactive group of dye.
- Reactive dye gives brighter shades and has moderate rubbing fastness.
- Dyeing method of reactive dyes is easy. It requires less time and low temperature for dyeing.
- Reactive dyes are comparatively cheap
- Reactive dyes have good perspiration fastness with rating 4-5.
- Reactive dyes have good perspiration fastness.
No comments:
Post a Comment