Brief classification of colourants according to application type:
- Acid dyes
- Direct dyes
- Reactive dyes
- Vat dyes
- Sulphur dyes
- Disperse dyes
- Basic dyes
- Chrome dyes
- Azoic dyes
Constituents, structure and properties. Hydrocellulose, oxycellulose. Action of acids and alkalis. Mercerization.
Impurities, pH, purification, hardness and effluent treatments.
Soap, anionic, cationic, amphoteric and nonionic.
Singeing, desizing, scouring, mercerisation. Bleaching (hypochlorite, chlorite, peroxide), fluorescent brightening agents. Advantages and disadvantages of various bleaching agents.
Theory of Dyeing
Dyeing of cellulose with direct dyes.
Properties and application. Aftertreatment.
Application to yarn, knitted goods, woven fabrics. Pad, jig, pad-batch, continuous dyeing, pad-steam. Polyester/cellulosic blends. Effluent treatment. Fastness properties, common faults.
Types, reducing agents, vatting, batch dyeing. IN, IW and IK classes. Semi-pigmentation, pre-pigmentation, acid leuco and continuous methods. Loose stock, sliver, yarn (packages and hanks), woven, semicontinuous – continuous, knit goods, faulty dyeing, solubilised vats.
History. Coupling components. Diazo components., Continuous and batch dyeing of stock, sliver, tow, hanks and knitted goods. Fastness properties.
History and chemistry. Cold dyeing, hot dyeing types and reactivity. Package, winch, jets, semi-and fully-continuous sequences possible. Aftertreatments and fastness problems.
Types and application methods.
Blends Dyeing procedures for polyester/cellulosic blends.
Dyestuff selection versus colour range. Reasons for selecting a certain class of dye, eg fastness, hue and cost.
Resin finishes for crease resistance. Special finishes for stain repellency, flame retardancy, waterproofing and softening.
Machinery used in processing.