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The development of new chemical structures for dyes is currently aimed at seeking products of lower ecological impact that conserve or even improve on the dying properties and level of quality. Recently, attention has been paid to amphiphilic structures that meet the needs of textile technology and show low toxicity and high biodegradability. In this work we synthesised disperse dyes that, in addition to the traditional azoic chromophoric system, contain glucosydic replacements in their structure whose hydrophilic nature should lead to greater biodegradability. The dyeing behaviour and final fastness of these dyes was analysed on polyester fibre and cellulose diacetate. The dyeing kinetics of polyester were studied as a function of the temperature. The activation energy, the exhaustion and the light and heat fastness were assessed. Only the exhaustion at equilibrium was assessed for cellulose diacetate. The conclusion had been reached that the introduction of such glycoside groups in an azoic chromophoric system did not necessarily affect the dying properties. According to the hydrophilic-lipophilic balance of the final structure it will give rise to disperse dyes that are more suitable for a hydrophobic fibre such as polyester or a more hydrophilic one such as diacetate, but in all cases the toxicity was reduced and the biodegradability of the waste increased. This therefore paves the way for research to define the possibilities and limitations of dyes with glycoside groups. [ABSTRACT FROM AUTHOR]

The recent appearance of this fibre has offered the advantages of a manufacturing process that pollutes less than conventional viscose and improves properties of wet tenacity and strength. The behaviour of lyocell fibre in absorption of direct dyes takes on particular importance in the corresponding dyeing stage during the chemical and industrial processing of this fibre. The objective of this study is to characterise the parameters influencing the process of absorption of direct dyes by lyocell fibres by analysing the equilibrium absorption isotherms of C.I. Direct Blue 1 dye. The experimental results were used to define equilibrium equations for interpreting the behaviour of the system through comparative analysis of the equations formulated by Nemst, Freundlich and Langmuir, and the characteristic free internal volume, V(l/kg), for lyocell fibre was calculated. In addition, the characteristic thermodynamic magnitudes of the system were calculated, i.e. the standard enthalpy, entropy and affinity of the dye, to allow satisfactory repetition and prediction of experimental results. Different operating alternatives can thus be compared quantitatively, obtaining the minimum data required for comparative evaluation of the process. [ABSTRACT FROM AUTHOR]