Sulpher

Different Dyes Which Are Used To Dyeing The Fabric & Yarn

Dyeing Fabric using different dyestuff is the most common things that every Textile Engineers should have to know. There are many kind of dyes are used to dyeing fabric. Maximum of them are suitable for fabric dye and yarn dyeing.

Dye staffs used to fabric dyeing are:

Direct dyes:

These dye staffs are generally sodium salt of sulphonic acid. They have direct affinity to cellulosic fibre. They are water soluble and needs salt addition in the dye bath. Should be applied at alkaline or neutral condition. Poor fastness to wash but cheaper for fabric dyeing.

Basic dyes:

These are generallyu ammonium, sulphonium or a uxonium salt. Famous for bright shade during dyeing fabric. Water soluble and application on cotton and other cellulosic fibre and leathers.

Acid dyes:

chemically acid dyes belongs to various subclasses such as nitro nitroso, monoazo, diazo, xanthance azine, quinoline, anthraquinone etc. they are water soluble and have affinity to wool, silk and nylon fibres to dyeing. They are applied to the fibres through neutral or acid dye bath.

Mordant dyes:

They are the oldest natural dyes. They have no affinity to textiles but can be applied to cellulose or protein fibres in order to dyeing fabric when they have been mordented previously with metallic salt. These dye staffs are capable of combining with metallic oxides to form insoluble colour on the fibre .

Sulpher dyes:

These are complex organic compounds containing sulphur. They are insoluble in water but sluble under reduced condition . they are usually applied cotton for cheaper shades, have high wet fastness but poor light fastness during dyeing fabric.

Azoic dyes:

These are not ready made dyes. Fibres are firstly impregnated with a coupling component like bita nepthol and then combined with a diazotized base to producer insoluble dye staffs into the fibre. Their main use on cotton but also can be used to dyeing wool silk and fur.

Vat dyes:

These are very fast color on cotton and insoluble in water. They are reduced by strong reducing agent to pr9oduce leuco vat and at this stage they are soluble in water. After impregnation they are again oxidized to their original insoluble form.

Reactive dyes:

These dye staffs directly combinds with cellulose by chemical bonding i.e. covalent bonds are produced. They have excellent wash fastness. Mainly used on cotton dyeing . can also be applied on wool, silk and nylin dyeing. Dyeing is carried out in an alkine bath.

Disperse dyes:

These dye staffs are very suitable for synthetic fibres for example polyester, nylon, acrylic, cellulosic acetate, etc. high temperature dyeing methods are suitable for these dye staffs but carrier dyeing method can also be applied.
In the above mentioned dyestuff, the Reactive Dyestuff is mostly used in today’s Textile Industry.

How to Garments Can Be Dyed by Sulpher Dyes?

Basically Sulpher dyes are used in case of Acid wash or Ball-washing. This is the time demanding matter to use the sulpher dyes in the knitted garments whereas it is now basically used in woven or denim garments.





The Dyeing of Garments by sulpher dyes are carried out as bellows:

Sulpher Dyestuff solution (Initial Process):

1. Use Sulpher Dye: On the basis of the percentage shade of the weight of fabric.
2. Sodium Sulphide: according to the shade card.
3. Soda Ash: 1/2 quantity of total dyestuff
4. Sulfaxil LTSN:  250~300 gm ( Sequesterant Agent)
5. Sulfonol WRW:  25 gm (anionic wetting agent)

In boiling water the sodium sulphide, soda ash, sulfaxi LTSN, Sulfonol WRW are to be dissolved. Then add the dyestuff here to be dissolved. Continue the processing for 5 to 10 minutes. Now filter the dissolved material before input it into the Dyeing machine.

Follow this step if your dyestuff quantity is large:

This process is taken when dyeing dark shades where if the quantity of the dyestuff are large. The entire items 1-5 are added in the drum machine containing around 150 liters of water. It is then thoroughly boiled for 10 to 15 minutes and the machine is kept running to ensure thorough dissolution. Then the liquor is made up t 300 liters with cold water. This will also bring down the temperature to 50to 60°C.

Prepare the dye bath as follows:

• Sulfonol WRW: 0.25 gram/liter
• Soda Ash: 2.5 grams/liter
• Sodium Sulphide: 5.0 grams/liter
• Sulfaxil LTSN: 0.5 gram/liter

Enter garments and run for 5 minutes at 30 to 40°C. Add dissolved dye gradually .Raise temperature to 60°C.

Add 20 to 30 grams/liter Vacuum salt and slowly raise temperature upto 90°C. Dyeing should be continued for 40 to 60 minutes.

Give overflow rinsing for 10 to 15 minutes.

Oxidation:

Finish oxidation process in a fresh bath containing

• Sulfaxil ECOX: 2 gm/litre
• Acetic Acid : 2 gm /liter

Keep it 20 minutes at 50 degree centigrade. Now Drain and rinse it in cold water for 5 to 10 minutes.

Finishing Process:

Wash the garment by using:

• Soap = 1 gm/liter
• Soda ash = 1 gm/liter

Process it for 15 to 20 minutes.

Now give the dyed garments a hot wash and then cold wash.