Relation between structure of dyes

the relation between structure of dye aand the chemical structure of the dye has a tremendous effect on the colour fastness or fastness properties of the dyes and as well as on the colour of the dyes

Example of some different dyes such as,

Disperse dye

The disperse dyes of thr following type,

relation between structure of dyes

if x = – cl , – H , – ch3 , – och3, etc.

and y = – ch3, – cl, – H, – och3, – NHch3

if I m talking about colour, colour ranging from yellow to blue can be obtained.


when the dyed fibre are exposed to light, the dye may change in colur. due to this, this is called phototropism Or it may be fading.

You can understand properly with the help of diagram.


if i m talking about phototropism, some time phototropism is a defect in textile dyeing process house. It may be Advantageously wed in increasing the light fastness dye.

In case of azo disperse dye the presence of a minimum no of attachable groups in the dyestuff molecules increases the light fastness oda dye.

An increase in e-, it may mobility of dye molecules decreases. and the light fastness as shown like this,

fastness properties

The explanation of e- withdrawing groups attached to N or ortho to amino groups increases the light fastness of dye.

Read MoreDyeing of mineral khaki materials? Recipe, process sequence.

Fastness Properties

The basic concept of fastness properties, this term is related with dyes. different dyes gives different fastness properties on the textile materials, but it is depend upon quality of dyes, and also dyeing processing.

Fastness properties generally show tolerance of the dyes on fibres towards the action of verious foreign agerries like light, washing, heat, rubbing, perspiration, milling and more. and fastness properties also show property of dyes.

Light fastness properties of dyes is expressed in term of grades.

Grades 1 – 8.

for example,

  1. Grade 1 – very poor
  2. Grade 2 – poor
  3. Grade 3 – fair
  4. Grade 4 – very fair
  5. Grade 5 – good
  6. Grade 6 – very good
  7. Grade 7 – excellent
  8. Grade 8 – outstanding

The dye gives proper washing fastness properties on the fabric. this mean, dye must be good washing fastness if the cloth on which it is dyed or printed is to be used for making garments.

Other wise staining of the garments with dyes striping from other garments occurs during washing of many garments together.

The chemical structure of the dye has a tremendous effect on the fastness properties of the dyes as well as on the colour of the dyes.

example of some different dyes such as

Disperse dye


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