Sulpher dyes are complex heterocyclic molecules or mixtures formed by melting or boiling organic compounds containing amino or nitro groups with Na-polysulphide and Sulpher. Sulpher dyes are so called as they all contain Sulpher linkage within their molecules.
Sulpher dyes are highly coloured, water insoluble compounds and have to be converted in to water soluble substantive forms (lucoforms) before application to the textile materials. This conversion is carried out by a treatment with a reducing agent like dilute aqueous Na2S. Since this lucoform of Sulpher dye is substantive to cellulosic materials. They are absorbed on the fibre surface. Then they are reconverted original water insoluble form of dye by oxidation. This oxidation is carried out by “airing” (exposure to air) or by using an oxidizing agent like Na-dichromate (Na2Cr2O7).
The reducing agents converts the “S” in dye in to –SH group and the Sulpher linkages. Then inside the material the thiols containing –SH groups are oxidized & thus reconverted to original form of dye.
This is shown in the bellow:
Dye-S-S-Dye + 2[H] = Dye-SH + HS-Dye
Dye-SH + HS-Dye +[O] = Dye-S-S-Dye + H2O
Sulpher gives best result (Bright Tone) when they are used to produce black, Black & brown shades but red shades cannot be obtained by Sulpher dyes.
Sulpher gives best result (Bright Tone) when they are used to produce black, Black & brown shades but red shades cannot be obtained by Sulpher dyes.
History of Sulpher Dyes
The history of Sulpher dyes may be summarized as below:
1. The first Sulpher dyes where made in 1873 heating saw dust, caustic soda and Sulpher. It occurred by chance when a reaction vessel containing Na2S was leaking and the saw dust was used to wipe the solution coming out. Later a cotton fabric come in contact with this contaminated sawdust and become stained.
2. The real pioneer of Sulpher dyes was vidal who produce vidal black (Name of Sulpher dye) by fusing para-phenylene diamine with Na2S & Sulpher in 1893.
3. In 1897 Kalischer produced Immedial Black FF by heating 2, 4-dinitro-4-dihydroxy diphenylamine with Na-poly sulphide.
4. In 1896 Read Holliday introduced a range of grey, brown and black Sulpher dyes by the action of Sulpher, alkali sulphides and many organic compounds.
The history of Sulpher dyes may be summarized as below:
1. The first Sulpher dyes where made in 1873 heating saw dust, caustic soda and Sulpher. It occurred by chance when a reaction vessel containing Na2S was leaking and the saw dust was used to wipe the solution coming out. Later a cotton fabric come in contact with this contaminated sawdust and become stained.
2. The real pioneer of Sulpher dyes was vidal who produce vidal black (Name of Sulpher dye) by fusing para-phenylene diamine with Na2S & Sulpher in 1893.
3. In 1897 Kalischer produced Immedial Black FF by heating 2, 4-dinitro-4-dihydroxy diphenylamine with Na-poly sulphide.
4. In 1896 Read Holliday introduced a range of grey, brown and black Sulpher dyes by the action of Sulpher, alkali sulphides and many organic compounds.
Method of manufacture of Sulpher dye
Aromatic Hydro Carbon Containing Hydroxy amino or nitro group = Sulpher Dye
Trade Names of Sulpher dye
Trade Names
|
Name of Manufacturer
|
Country of origin
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Calcogen
|
Dyes Dept. American Cyanamid Co.
|
USA
|
Pyrogene
|
Ciba
|
Switzerland
|
Thional
|
Sandoz
|
Switzerland
|
Solfo
|
ACNA
|
Italy
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Sulfogene
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Du pont
|
USA
|
Thional
|
Imperial
|
UK
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Mitsui Sulpher
|
Mitsui Chemicals Ind. Co. Ltd
|
Japan
|
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