Reactive dye || Reactive dye features || Reactive dye classification
Reactive dye is only dye that reacts with the textile fibre & makes covalent bond with fibre.Under the suitable condition it reacts with –OH or –NH2 of the fibre & forms covalent dye substrate linkage.
DYE-SO2-CH2-OSO3Na + HO-Cell ———- D-SO2-CH2-CH2-O-Cell + NaHSO3
FEATURES of REACTIVE DYE
1. Water soluble.
2. Reacts with fibre & makes covalent bond.
- works in alkaline condition Ph >10.
4. Dye cellulosic ( Cotton,viscose,linen,flax, jute) & Protien ( wool,silk)
5. Excellent fastness property.
6. widely used
8. Needs salt & soda for dyeing.
9. Anionic in nature.
WHY CALLED REACTIVE DYE
They contains reactive group in their structure. It reacts with fibre end groups. That”s why it” s called reactive dye.
Dyes contain several group. Such as :
W-water soluble group ( -NH2, -NH-CH3, -OH, -NO3 COOH, SO3Na ,NO2)
D-chromophore group ( anthraquinone, azo , phthalocyanine, metal complex)
Q– linker (-NH-, -NH-CO-, -NH-CO-NH- )
RG– reactive group ( vinyl suiphone, pyrimidine, triazine )
X– leveling group
All this part make the dye water soluble & strongly attached with the fibre.
) ON BASIS OF REATIVE GROUP
) ON BASIS OF REATIVITY
A) ON BASIS OF REATIVE GROUP
1.Hetaro cyclic copound
1. vinyl acryl amide
2. vinyl sulphonamide.
B.ON BASIS OF REATIVITY
1. ON THE BASIS OF TEMPERATURE & METHOD
A. Cold brand
B. Medium brand
C. Hot brand
MAIN PROBLEM OF REACTIVE DYE
Main problem of reactive dye is hydrolysis . As Reactive dye contains reactive part which mainly reacts with cellulosic -OH group. Unfortunately water contains -OH group. As huge amount of water is used for dyeing reactive dye first reacts with water & waste a lot of dye. This is the main problem of reative dye.
DYE- Cl + HO-Cell——– DYE – O-Cell + H-Cl
DYE-Cl + H-H0———- DYE-OH + HCl