Characteristics & Properties of reactive dye?


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
Br (bromine) – 64-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.

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