Discontinuous Dyeing With Natural Dyes

Accompanied by the increasing awareness of the environmental protection, the research of ecological textile has become the hot spot. The voices of return to the nature and health care have become stronger. Although the synthetic dyes have made a great progress for textile industry, in the process of dying, the waste water is difficult for biological degradation, causing serious environmental pollution, and some dye intermediates are toxic, carcinogenic. The natural dyes have a vide variety of sources, besides it is renewable when used in textile dyeing and finishing, and non-toxic to humans, so the natural dyes become the focus of research once again.In this paper, it was investagted the natural dyes by using the special resources in French, using the local plants of mignonette, hematoxylon, madder, lavender, French marigold and the animal coccid as raw materials for the extraction of natural dyes. The extracted natural dyes are applied to cotton fabric. The experiment of natural dyes extraction is carried by orthogonal methord, from which select the best condition for extraction. For the application of the natural dyes on cotton fabric, the research is focus on the process optimization and find out the best dyeing condition. At last the optimum conditions of dyeing were determined by the determination of the relevant parameters.The exhaust dyeing processes are carried out with different mordant such as tannin, iron sulfite, alum etc. (the mordant may be added before, during or after the dyeing process to the fabric). An analysis was made of the effect of different process and different mordant. The results show that the mordant can not only enhance dye depth but also improve colour fasteness. At last the optimum conditions of dyeing were determined by the determination of the relevant parameters.The improvement of color fastness (washing fastness and light fastness) was also discussed in this paper. By using the fixing agent treatment and mixing the mordants for the improvement of fastness, the results showed that the washing fatness of dyeing fabric have improved (up to 3 or more), but there is no significant improvement in light fastness results. And there is an adverse effect on the color of fabric; and the fixing agent can be added to improve the washing and light fastness, there is about a half-level increase, mordant blending can make some natural dyes improve the washing fastness, but no significant improvement in the light fastness.