Dye Diffusion‐The Key to Efficient Coloration

Abstract

More than any other factor, the rate and degree of diffusion of dves into the individual fibres composing any textile substrate control the productivity, reproducibility and the quality (with respect to appearance and sometimes the fastness properties) attained in each process. Using direct (fibre cross-section) measurement of the degree of penetration of dyes into nylon, polyester and acrylic fibres, under a variety o f application conditions, the relationships between dye penetration and visual colour yield has been determined with fibres differing in cross-sectional shape and delustrant content.The present interest in saving energy, time and water has led to numerous processes resulting in 'ring-dyeing: Batchwise dyeing for relatively short times or at somewhat abnormal temperatures, and continuous dyeing by rapid steam-fixation techniques are examples which have been investigated to define application conditions that might be expected to cause problems in bulk-scale production. Multi-layer Diffusion MethodAnother simple method for determining comparative rates of dye diffusion into any polymer which is available as a clear thin fiim, is the BASF Kombitest [ l ] , which has now been

The Combined Synthesis and Coloration of Poly(lactic acid)

“…This difference is shown in Figure 7 where distribution of color through DyeCat PLA (Figure 7 a) is homogenous, and that for a conventionally dyed PLA fiber (Figure 7 b) is nonhomogenous and the dye molecules aggregation; this heterogeneity often leads to the phenomenon known as "ring dyeing", which results in an observed reduction in color strength. [23][24][25][26] In general, homogenous distribution of the dye through the cross-section of a fiber tends to yield higher K/S (Ratio of absorption to scattering, a measure of the visual color strength) values in comparison with those for fibers in which the dye is primarily located at the periphery. [23][24][25][26] Therefore, the color strength of DyeCat polymers will be in excess of those obtained through conventional dyeing processes, allowing lower dye levels to be used and no waste typical of a conventional dyeing procedure.…”

Dyeing with Disperse Dyes

“…This is because of the diffusion phases shown in Fig. 16, including convective transfer through the liquor adsorption and molecular diffusion into the fibre, is the rate-determining step (Dawson & Todd, 1979). Where the time needed for the adsorption phase is largely influenced by the machine conditions, in the diffusion phase the time required at top temperature is directly related to the diffusion characteristics of individual dyes and dyeing depth, but generally, the standard time is 10-20 minutes for dyeing up to pale shades, 20-30 minutes for medium shades and 30-35 minutes for deep shades.…”

The use of reflectance measurements in the determination of diffusion of reactive dyes into cellulosic fiber

“…To date, industrial dyehouses have not considered the measurement of dye diffusion as an everyday tool because the currently available methods are either time consuming, indirect or involving the use of sophisticated laboratory procedures or complex mathematics . The currently available methods for determining dye diffusion are: examination of fiber or yarn cross‐sections, multilayer of a clear polymer thin film diffusion methods, microdensitometer method, rate of dyeing method, and laser scanning confocal microscopy method . This article presents an easy, direct, and industrially applicable method for determining the dye diffusion.…”