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A numerical approach to the relationship between depth of dyeing, dyeing temperature and rate of dyeing (time necessary for complete exhaustion) has been studied for the cationic dye/acrylic fibre dyeing system. A method for determining the optimum dyeing conditions from two absorption curves at two dyeing temperature levels has been developed. A calculation system based on these relationships has proved to be applicable and valuable in practical dyeing. D G Heane, T C Hilland J Park, J.S.D.C., 95 (1979) 125.A series of model alkoxychlorotriazinyl reactive dyes has been synthesised. Each compound, in turn, has been hydrolysed in dilute sodium carbonate solution and product ratios and rates of reaction determined. It has been found that the nature of the alkoxy group significantly influences the course and rate of the reaction.

The levelling properties of nine reactive dyes containing one or two sulphatoethylsulphone reactive groups or one sulphatoethylsulphone and one monochlorotriazine reactive groups have been investigated. A novel test method specifically applicable to reactive dyes has been used in order to evaluate levelling. Undyed and dyed cotton samples were simultaneously dyed in the same bath and the fractions of the additional dye fixed on each of the cotton samples were determined afterwards. A dye distribution index has been proposed that predicts reactive dye levelling according to whether the index exceeds 50% or not. The index was found to depend not only on the nature of the dyes, but also on the concentration of the dye fixed on cotton, the dyeing temperature and the salt concentration in the dye liquor. In redyeing tests the degrees of primary and secondary exhaustion and of dye fixation were measured as a function of concentration of the dye fixed on cotton. Finally a satisfactory correlation was found between the index and the classical inorganicity/organicity value of the dyes. The results also suggest that the levelling properties depend on the degree of dye aggregation.

Eighteen isomeric dyes, each based on phenylazo-H-acid and containing two reactiue groups, namely a monochlorotriazine group and a sulphuric acid ester of Phydroxyethylsulphone, were applied to cotton fabric by an exhaustion process at 60°C. The following properties were studied: spectra, uptake curues ofthe dyes before and after adding sodium carbonate, affinity, diffusion rate, and rates of hydrolysis and of reaction with cellulose, as euidenced by fixation and colour yield. S o m e significant correlations were found, but some missingorpoorcorrelations indicated that there are further parameters or relationships between parameters that remain to be elucidated.