Solvent dyeing is a dyeing process carried out from a continuous non-acqueous phase. Here solvent is used as dyeing media. But water may be added to assist dyeing process. Since the introduction of hydrophobic fibers like cellulose acetate in 1920’s solvent have been considered for dyeing because it was not possible to dye such fibers with ionic dyes and water.
Characteristics of Solvents:
An ideal solvent for Textile processing should have the following characteristics –
1. Non- toxic.
4. Inert to textile materials.
5. Stable to repeated distillation.
6. Low Specific heat.
7. Low heat of evaporation.
8. Readily available.
9. Economic feasibility.
Types of Solvent Used in Textile Processing :
Some solvents of chlorinated hydrocarbons of aliphatic series posses most of the mentioned requirements and hence are being used as solvents are extensively used such as –
1. Tri-chloro Ethylen (TCE).
2. Per-chloro Ethylen (PCE).
3. Methyl Chloroform (MC).
All three solvents are almost equally suitable but tri-chloroethylene has very high stability to decomposition and hence isomers preferable.
Advantages of Solvent Dyeing:
1. High wettability and dyeability.
2. Rapid dyeing with minimum energy requirements.
3. Better levelness and dye yield compared with better fabric aesthetics.
4. Solvent is being recycled, so the effluent control problem is eliminated.
5.Less time required.
Disadvantages of Solvent Dyeing:
1. Solvents are expensive, so higher production cost
2. Problem in equipments availability.
3. Existing dye can not be used in full range.