Dyeing of 100% cotton yarn with Azoic Color

The azoic dye is not ready-made dyes like reactive dyes. Two components are aromatic diazonium salt and an aromatic hydroxy compound. In the application of azoic colors, the first step is selecting the best suitable diazo and coupling components combination of a particular purpose is to decide which of the naphthols can be used in conjunction with the available diazo components to give the color closest to the chemical shade and depth.

Nature Of sample: 100% Cotton Yarn (Pre-Treated).

Apparatus Required:  i) Beakers. ii) Glass Rod. iii) Pipette. iv) Measuring Cylinder. v) pH meter.        vi)Tripod Stand. vii) Gas Burner. viii)Thermometer. ix)Pot. x) Electronic Balance

Process Sequence: 

Recipe of Naphtholation,

                                   Sample weight= 10 gm

                                       Wetting agent=.5 g/L (S.solution-1% )

                                       β Naphthol= 2% owf (S.solution-2% )

                                       NaCl=1 g/L (S.solution-1% )

                                      NaOH=1 g/L(S.solution-1% )

                                      Temperature = Normal Temperature 

                                      Time =15 Min

                                      M:L=1:20

                                      pH=

Recipe of Diazotization,

                                 Sample weight=10 gm

                                     Diazotized color base=2% owf (S.solution-2% )

                                     NaNO2  =  1 g/L (S.solution-1% )

                                     HCL  = 1 g/L(S.solution-1% )

                                 Temperature =0-5°C

                                  Time=15 Min

                                      M:L=1:20

                                      pH=

      Function Of chemical:

       Wetting agent: Reduce surface tension. 

       β Naphthol: Generally used for naptholation (very important stage) treatment. 

        NaCl: used to remove excess naphthol.

        NaOH: Alkali is used to convert naphthol to soluble Na- naphthenate. Alkali makes naphthol substantive to cotton fiber.

        Diazotized color base:

        NaNO2 &HCl: Both are used for the diazotization process (for making Benzene diazonium chloride).

          Common salt: Used as an electrolyte to increase the substantivity of naphthol to fiber.

Calculation: 

    For Naphtholation,

                           Sample weight = 10 gm

                           Total Amount of solution= (20×10)ml

                                                                    =200ml

                            Wetting agent= 200× .5×100/1×1000

                                                             =10 ml

                          β Naphthol= 10×2%/2%

                                         =10ml

                           NaCl= 200× 1×100/1×1000

                                         =20 ml

                           NaOH =200× 1×100/1×1000

                                            =20 ml

                                  Initial Water for Naphtholation= 200-(10+10+20+20)

                                                                                         = 140 ml

      For  Diazotization,

                             NaNO2 =200× 1×100/1×1000

                                                  =20 ml

                                   HCl =200× 1×100/1×1000

                                   =20 ml 

                              Color base= 10×2%/2%

                                               = 10 ml 

                                      Initial Water for Diazotization= 200-(20+20+10)

                                                                                           = 150 ml

             Process curve :



1st step,

Fig: For Naphtholation

2nd step,

Fig: For Diazotization

  Precaution:

1. We have to maintain laboratory precautions very carefully.
2. Every chemical we take should be taken accurately by pipette and should be taken very carefully.
3. We should be very careful during the time of working with a gar burner.
4. We should have to maintain the temperature accurately.