Effect of dispersing agents and substitution on the dyeing and spectroscopic properties of disperse dyes.

A number of monoazo disperse dyes were prepared and milled with different d ispersing agents in a finely divided form as dispersions. The average parti cle size of all dispersions were measured to be under 1 mum for all dyes st udied The officienoies of dispersing agents used were h order : Ligninsulph onate > Bad > Tamol > Monolans. Low concentrations of Tamol were required f or 81 type of dyes as compared to S2 type. The capability to withstand high temperature (130 degreesC) during dyeing was determined by the change in c hange particle which increased Ra hating but remained under 1 mum except fo r Berol which showed no remarkable change in particle size. The fastness pr operties studied should higher values for A2-D2 aia which h ve cyao-ethyl g roup in their coupling component than A1-D1 series with hydroxyl group in t heir structure. On tbe whole fastness value to wash, light and heat of basi c dyes S1 (3-4) ad S2 (4-4.5) series increased with the introduction of ele ctron withdrawing grape in tbe dye structure ad remained around 5. The effe ct of substitution to showed bathochromic and hypsochromic shift ha 8 to 25 nm. The effect of dispersants on the colour properties of dyes studied wer e in order Ligninsulphonate > Tamol > Monolan > Berol. All the dyes showed a good co-relationship between the data obtained during these investigation s.