Studies over some new natural dyers
Programme: PNCDI II - Capacitati - Module III
National Institute of Research-Development for Textile and Leather, Bucharest, Romania
Indian Institute of Technology, Faculty for Ecological and Analytical Testing, Kanpur, India
General Frame : In the last couple of years concern for the environment has created a deep interest in natural dyes. This is further enhanced when toxicological effects of synthetic dyes during production and harmful effects on skin during wearing are being more and more known.
The domestic market requirement of natural dyes when compared to the current off take of synthetic dyes represents a mere 10%, but their scope is unbound in the era of Ecofriendliness. Especially in the handloom sector where greater emphasis is being given to Ecotex.
Ecological considerations are becoming important factors in the marketing of consumer goods where textiles make a major export market.
Scientific and technical objectives:
- selecting plants and vegetable wastes with tinctorial properties;
- dyes extraction;
- identifying the structure of these dyes;
- establishing the dyeing technology with natural dyes taking into account a maximum tinctorial capacity;
- characterization of the properties of the dyed textile materials;
- the concentration and standardization of the dyes;
- characterization of the natural dyes according to European regulations;
- promoting ecological textiles on internal market and at the export.
1. Extraction of the natural dyes from plants as onion and fir, Punica granatum and Rheum Emodi (received from Indian partner).
2. Natural extracts analyses.
3. Dyeing experiments of the textile materials with extracted dyes
4. Caracterisation of the textile materials dyed with natural dyes.
1. Naturals dyes extraction technologies from plants by:
- extraction in boiling water;
- hydrodistilation: dyes extraction at high temperature with water
- Soxhlet extraction with organic solvents or mixtures of organic solvents / water
2. Analyses methods of the obtained extracts: UV-VIZ and FT-IR spectrophotometry HPLC, thin layer chromatography
3. Dyeing technologies of the cotton and wool textile materials with natural dyes extracted from plants as onion, fir, Punica granatum and Rheum Emodi (sent by Indian partner).
4. Analyses methods of the dyed materials with natural dyes:
- physical and mechanical analyses;
- trichromatic coordinates;
- dyeing fastness to light, acid/alkaline sweat,
- ecological analyses: heavy metals, pesticides, formaldehyde, etc.
- analize biological analysis.
The results demonstrated the following:
- the natural dyes obtained from vegetable materials are ecological: they do not contain heavy metals, formaldehyde, pesticides, etc.;
- the colors varies in function of used vegetable materials, the extraction method, the dyeing technological parameters. Generally, the nuancele varies from beige to dark brown.
- the dyeing fastness varies in function of used dye type and of the dyeing technological parameters. As example, in case of Punica Granatum dyeings, the dyeing fastness to acida and alkaline sweat is comparable with thos of synthetic dyes. But the dyeing fastness of the materials dyed with Rheum Emodi are less resistent at sweat and light;
- similar nuances were obtained in identical dyeing conditions;
- the dyed materials with Punica Granatum have anti-bacterial effects
- the materials dyed with some of the naturals dyes have beneficial effects on human health. As example, the textile materials dyed with Punica Granatum have anti-bacterial effects.
THE ADVANTAGES OF USING NATURAL DYES:
- reducing the degree of environment polution;
- making ecological agricultural productions;
- valuing the spontaneus flora and enriching the areas of culture by diversifying various sorts of plants.