REACTIVE DYE

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.

  1. works in alkaline condition Ph >10.

      4. Dye cellulosic ( Cotton,viscose,linen,flax, jute) & Protien ( wool,silk)

      5. Excellent fastness property.

      6. widely used

      7. cheap

      8. Needs salt & soda for dyeing.

      9. Anionic in nature.

WHY CALLED REACTIVE DYE

They contains reactive group in their structure. It reacts with fiber end groups. That”s why it” s called reactive dye.

STRUCTURAL FEATURE

Dyes contain several group. Such as :

        W-D-Q-RG-X

   W-water soluble group ( -NH2, -NH-CH3, -OH, -NOCOOH, 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 fiber.

CLASSIFICATION

        ) ON BASIS OF REATIVE GROUP

         ) ON BASIS OF REATIVITY

A) ON BASIS OF REATIVE GROUP

      1.Hetaro cyclic copound

             a. Triazine

             b. Pyrimidine derivative

             c. Quinonaline

       2.Activated vinyl

             a.vinyl sulphone

                  1.  vinyl acryl amide

                  2.  vinyl sulphonamide.

B.ON BASIS OF REATIVITY

  1. Lower reativity

         2. medium reativity

         3. higher 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 cellulose -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.