Textile Dyeing in Ionic Liquids
Lately, the scientific as well as practical (application-oriented) interest in the so-called ionic liquids (IL) has been growing. IL represent an important class of materials, called “Green Solvents”. In general, IL are to be understood as ionic substances, that are already fluid from room temperature up to 120°C and that are often thermo-stable far beyond 200°C. IL excel by their extremely low vapour pressure, which makes them easy to handle in contrast to organic solvents. IL show high and temperature related dielectric constants, therefore displaying outstanding solubility for different substances, such as cellulose, keratin, and silicones.
Preliminary work at DTNW has shown that ionic liquids are moreover suitable as dyestuff medium for textiles (e.g. for disperse dyestuffs, cationic dyestuffs, reactive and metal complex dyestuffs), with which it is possible to proceed to real dyeing operations under atmospheric printing conditions.
Objective & Route
The aim of the research project is to develop the principles of an operational technique to dye natural and synthetic fibres from ionic liquids. This will in particular be systematically investigated for the commercially most important fibres from cotton and polyester (PET, PBT, PTT) but also for other types, such as wool, polyamide and Polyacrylonitrile. This procedure allows a pressure free operation at high temperatures with minimal air pollution. Conventional dyestuffs that are difficult to solve can be examined and applied in the new solvent system. Recycling strategies and toxicological assessment for IL will not be dealt with, because this theme is already intensively examined both by the chemical industry as by several colleges – with highly promising prospects. During the project however the progress regarding these topics will be followed.