THE STUDY ON THE DYEING OF CELLULOSE ACETATE: (PART VII) THE COLOUR AND THE TEMPERATURE IN DYEING

The effect of the temperature to the colour in dyeing of cellulose acetate was studied and it was shown by pursueing the change of the maximum purity point in the curve between the luminosity and the purity through the chromatical method that more brilliant colours are generally obtained at the low temperature than high. This seems to be due to the fact that when the distribution of the dye in the fibre section is observed, the dye concentration at the fibre surface is usually larger in the case of the low temperature dyeing that the high when the total concentration in the fibre is same. More brilliancy is given at the low temperature dyeing that at the high as it may easily be understood from the curve on the luminosity and the purity of the colour given in the pravious paper, No.5. At the same time the blue dys which seems rather exceptional in the experiments is presumably due to the excessive concentration of the dye in the surface of the fibre beyond the maximum purity point, and it is explained from this point of view that the so-called apparent dyeing, seen often at the pretty low temperature or the early period of the dyeing, may also give darker shades.