In this thesis, the influence of impregnation bath composition on the quality of digital printing with reactive dyes on 100% cotton fabric was investigated. Nine impregnation baths were prepared: one reference bath used in industrial production, two formulations supplied by the manufacturer, and six laboratory-prepared formulations. All baths were prepared in equal quantities (20 kg), ensuring uniform impregnation conditions. The fabric was pre-treated, impregnated on a tenter frame dryer, digitally printed with reactive dyes, and subsequently post-treated to remove unfixed and hydrolyzed dyes.
Colorimetric values in the CIELAB color space were measured on the printed samples, and the color difference ΔE* ab, color depth K/S, and degree of print penetration were determined.
The results confirmed that the composition of the impregnation bath significantly affects the visual properties of printed samples. The KEOJET RSL 3 and TUBIJET DOO2 baths achieved the highest chromaticity values CIE C* ab, the lowest CIE L*, and the greatest color depth K/S for most color samples, resulting in darker, more intense, and more saturated prints. In addition, these baths exhibited the lowest degree of penetration, indicating that a greater proportion of dye remained in the surface layer of the fabric. Conversely, the baths with the highest penetration levels (KEOJET RSL 5 and the Tekstina standard bath) produced lower color depth, confirming an inverse relationship between dye penetration and surface color intensity.
It was found that the type of alkali used alone does not sufficiently explain the differences observed between the impregnation baths. The key factors influencing dye migration and the relationship between K/S and penetration are polymeric additives that form a surface film on the fabric and regulate the amount of dye retained in the face layer. Therefore, optimization of impregnation baths requires an appropriate balance between urea, alkali, and polymeric components, as well as the careful selection of surfactants, thickeners, buffers, and defoaming agents, all of which collectively influence the final visual appearance of the print.
Based on the conducted research, it can be concluded that a properly formulated impregnation bath significantly improves color depth and brilliance, motif sharpness, and controlled print penetration. Since this study primarily focused on the visual aspects of print quality, color fastness properties were not examined in detail.
Key words: digital textile printing; reactive dyes; impregnation baths; cotton pre-treatment; colorimetric measurements; print penetration; visual print properties.
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