Time Dependent Dye-uptake Variations in 150 f44 Tilobal Polyester Yarn
May 27th, 1975
Systems Technology Group Technical Note, ICI Europa.
S F Bush with S Baillie-Strong.
Summary and Conclusions
- Major variations in texturised yarn dye-uptake were observed which correlate strongly with time at spinning and clearly moved in sympathy with pack pressure and Draw Tension Integrator date at spinning.
- The most likely cause of these variations was differences in moisture content of the polymer fed to the driers causing hydrolysis and molecular weight changes in the spun yarn.
- These variations caused about 20% of the total package-to-package variability with shifts of almost 2 dye-shades in mean level in about 36 hours. These magnitudes are for Turquoise CG dye at pressure – a typical continental customer requirement. The recommended quality control dyestuff, Navy D2G, probably underestimates these variations.
- The cause of gross variations in polymer moisture content should be eliminated. However, since the polymer transport system (Tote Bins) cannot be hermetically sealed and since the chip moisture content is below atmospheric humidity, some variations will always be present. A drying control strategy to deal with these variations with the aid of a drying model should be developed.
- The same magnitudes of changes in initial water content and yarn i.v. have been obtained by other investigators on 167 f30 at various times from January 1974 to the present.
- The calculated i.v. to water content sensitivities agree closely with measured values.