Topics of Discussions1. Review on "Sulphur Dyeing"2. History of Sulphur Dyes

3. Synthesis of Sulphur Dyes

4 Ch i l P i i l f S l h D4. Chemical Principles of Sulphur Dyes

5. Structure of the Sulphur Dye market

6. Sulphur Dyeing Process

9. Benefits

History of Sulphur Dyesy p y

1873 Chance discoveryAttempt to absorb an alkaline sulphuric liquor with sawdust cotton fabric that came into contact with the substance turned yellowish brown

1893 First sulphur dyes from defined chemical compounds produced by Vidal formed

Significant Development

1893 First sulphur dyes from defined chemical compounds produced by Vidal formed dyes when heated with sulphur or with sulphur and alkali

1897 G. Kalischer of Cassella developed Immedial Black V deep-bluish-black hue

1899 Agfa introduced "Sulphur Black T" produced from inexpensive 2,4 dinitrophenol Sulphur Black 1 best-known sulphur dye

1909 L Haas and R Harz discovered Hydron Blue (Vat Blue 43 produced form carbazol 1909 L. Haas and R. Harz discovered Hydron Blue (Vat Blue 43, produced form carbazol leucoindopheonol (VIII)

1927 Wolf von Heiman discovered Indocarbon (Sulphur Black 11)

Synthesis of Sulphur Dyes

Synthesis route for C. I. Sulphur Black 1y p

Saponification

2,4 Dinitrochlorobenzene 2,4 DinitrophenolateSodium salt

Sulfuration

2,4 DinitrophenolateSodium salt

Synthesis of Sulphur Dyes

Proposed structure for C. I. Sulphur Black 1

F. Gordon and P. Gregory, Organic Chemistry in Colour (1983)

Chemical Principles of Sulphur Dyes

Small sulphonated polymersProduced from organic intermediates with sulphur

b l b k h dCannot be split back into the starting products

Halogen-free

Chemical reactions in Sulphur Dyeing Process

Reduction cleavage of disulfide bridgesSoluble in aqueous alkaline solutionsSo ub e aqueous a a e so ut o sAffinity for textile fibre

Oxidation of dyestuffs on fibreInsoluble in waterPigment cannot migrate out of fibre

Equation: R - S - S - R + 2e- ↔ R - S- + R - S-q

Technical focus

90% of all continuous processes is one-bath pad-steam

80% of all exhaust processes are navy and black shades

Denim application on Indigo rangespp g g

Product Name: C. I. Sulphur Black 1

Required Properties:

Reduced sulphide quantity in dyestuffs

Sulphur Black to be used for Denim

Reduced sulphide quantity in dyestuffs

Flexibility in use

Either being reduced with sulphide or sulphide-free reducing agents (ecological issues)

High Concentration (In case of Liquid Sulphur)

Sulphur Dyeing Process

ReductionConvert the dye into soluble leuco form by adding reducing agent and alkali.Oxidation

Dyeing mechanism

Convert dyestuffs in fibre back into insoluble pigment form by adding oxidizing agent.

Sulphur dye range

Economic efficiency

Environmental aspects

Reducing agent-Selection depends on

Environmental aspects

Dyeing process

Ecological reducing agents

Hydrosulfite/Glucose This so called binary system forms sulfuric acid in dye bath which acts as an optimum reduction system for sulphur dyeing. The redox potential of this binary system is lower than that hydrosulphite alone. Therefore, there is no risk of over reduction and thus destruction of sulphur dyes.

Glucose Dextrose Monohydrate-Clariant recommends Glucose in combination with Caustic soda (Can be applied to other dyes but as instructed by the manufacturers & it might affect y gcolour yield).

Procedure used (continuous or exhaust dyeing)

Fastness requirements

Shade

Oxidizing agent-Selection depends on

Shade

Dosing requirements

Costs

Environmental aspects

1 H d id ( id l d) H 4 5 70 °C

Recommended oxidation methods1. Hydrogen peroxide (acidulated), pH 4,5, 70 °C

2. Hydron peroxide (alkaline), pH 10, 40 °C

3. Sodium bromate/metavanadate (acidulated), pH 4,5, 70 °C

Notes on oxidation methodsOxidation with hydrogen peroxide in an alkaline medium is a simple method and produces l h d b t l d b k i it d t f t Thi th d i d h d i clear shades but only drawback is it reduces wet fastnesses. This method is used when dyeing

wound packages.Oxidation with hydrogen peroxide in an acid medium is a reliable method. The fastness and shades obtained are comparable with other common oxidation methods.Oxidation with sodium bromate contributes to slightly formation of AOX in waste water. It takes place rapidly and is a reliable method.

Black dyeings oxidized in an acid medium requires a final buffer with soda ash and/or sodium acetate to prevent any tensile strength loss.

One-Bath Pad-Steam Process, pick-up 70%, 1 min steaming at 102 °C

Fabric : 100 % Cotton woven fabric

Shade Comparison-Depending on the Oxidation Method

Fabric : 100 % Cotton woven fabricDyeing : 30 g/l Hydron Blue R Stabilosol

OxidationHydrogen peroxide, pH 4 - 4,5, 70 °C

OxidationHydrogen peroxide, pH 10, 40 °C

OxidationSodium bromate, pH 4 - 4,5, 70 °C

Wetting AgentsOnly anionic wetting agents can be used for dyeings with sulphur dyes

Check the wetting agent by the "Hydron Blue Test“ prior to use.

Nonionic wetting agents can lead to precipitation of the dye

Result will be unevenness less yield poor rubbing fastnessResult will be unevenness, less yield, poor rubbing fastness.

Exhaust DyeingCommon process

100

110 °C

45' 95 °C

60

70

80

90

100 45 95 C

3 °C/min

10' 75 °C

20

30

40

50

60

5' 5' 5'

10'

10'cold rinse

drain

warm rinse

drainRinse inoverflow untilliquor is clear

Reducing agentDye

0

10

20

0 20 40 60 80 100 120 140 160 180 200 220 240min

cold rinse

OxidationSalt

Alkali

After-treatment in open-width washer (5 compartments)

1 Rinse at 20-40°C, water through put 4-6.0 l / kg fabric

2 Oxidize with 4-5.0 g/l a suitable oxidizing agent, 70°C, pH 11.5–12.5 (replenishment l ti f 40 50 /l O idi i t f d 0 1 l/k f b i )

Boxes

solution of 40-50 g/l Oxidizing agent, feed 0.1 l/kg fabric)

3+4 Soap with 1-2.0 g/l detergent, pH 9-10, 2 ml/l acetic acid 80%, 95-100°C (must be kept constant), replenishment 10-20 g/l detergent, feed 0.1 l/kg, counter-flow principle

5 Rinse at 40°, add acetic acid to set pH 5-6 (check with pH meter). Up to 80°C is possible, if cylinder dryer follows.

Remarks: keep in all compartments selected temperature, pH and water-flow constant

To cover typical indigo blue shade

Why to apply a sulphur top?

To changes the Indigo shade

To get more deep bluish black

To have Special wash-down effects

To eliminates contamination of indigo dye bath with sulphur dye

Other Dyeing Processes

Dyeing of Cellulose/Polyamide blended fabric with Sulphur BlackOne-bath one-step black dyeingShort dyeing time

Dyeing of Polyamide micro-fibreHigh light and wash fastnessDeep Black

Dyeing of cationic ally pre-treated Cottonwash-out look

Benefits

l h

Economical dyes for muted and deep shades like dark brown, olive, navy and blackthis is the shade range that predominates in sulphur dyes

Favourable cost structure at process

For Black very high perspiration and wet light fastness

Benefits for using Sulphur Dyes

Especially suitable for deep shades with excellent appearance of the goods

Good consumer fastness properties

Various possibilities for ecological dyeing processes