In situ synthesis of pigments in keratin fibres

• In-situ-Synthese von Pigmenten in Keratinfasern

Kurniadi, Juliana; Möller, Martin (Thesis advisor); Böker, Alexander (Thesis advisor)

Aachen : Publikationsserver der RWTH Aachen University (2015)
Dissertation / PhD Thesis

Aachen, Techn. Hochsch., Diss., 2015

Abstract

In the present work an alternative dyeing method based on in-situ synthesis pigments in keratin fibers e.g. wool and hair is illustrated. Permanent iron dyes and dyes formed by direct diazotation of wool are developed for colouring wool, while quinone based pigments with and without metal are investigated for dyeing wool as well as for human hair. In all cases, application parameters as well as the process parameter are thoroughly investigated. Iron salt with series of benzoic acid is used as a substitute for hazardous chromium containing mordant dyes for wool. Since the colour pigments are formed in situ, coloured effluents which can eventually lead to toxic waste are not produced. By this method excellent washing and light fastness are obtained. This dyeing procedure was accomplished under mild reaction condition which further prevented any additional damage to the wool fibres contrary to the conventional method used. Further quinone based pigments from pure 2,5-dihydroxy-1,4-benzoquinone (DHBQ) are developed with and without using metal complexes for dyeing wool and hair. It was shown in this work that DHBQ as ligand has the potential to be applied in commercial wool dyeing procedures. The results showed excellent washing fastness and good rubbing fastness. The synthesis runs under mild condition and therefore no significant damage to the wool fibres was observed.In situ formation of colour pigments from pure DHBQ has a potential to be developed as a novel and environmentally friendly long lasting hair colouration. For dyeing hair with these pigments no additional pre-treatment is required to achieve a range of different colours. Mild dyeing conditions used in this process prevent mechanical damage to the hair compared to bleaching used for traditional hair dyeing. Taking the advantage of the existence of amino acids in wool, in situ dye formation by direct diazotation using very small quantity of different diazonium salts was investigated. This process is shown to be dependent on pH, reagents and reactivity of the diazonium salt. Although the molar ratio of the amino acid to the salt was very low, intense colour shades are achieved. Summing up, reactive and non-toxic dyes with a variety of shades are developed based on the ship-in-the-bottle concept. The developed procedures may easily be used for dyeing different fibres.

Institutions

• Chair of Macromolecular Chemistry [154610]
• Department of Chemistry [150000]