Digital Printing Knitted Fabrics made of Polyamide, Cotton and Blends thereof

Knitted fabrics with different compositions, i.e. 100% cotton (CO), 100% polyamide (PA), and a blend of 50% cotton and 50% polyamide (CO/PA), were digitally printed with reactive dyes. The cotton fabric was pretreated with a conventional alkaline solution of alginate thickener, sodium carbonate and urea (A). The polyamide fabric was pretreated with an acidic solution of galactomannan thickener (GM). The CO/PA blend was pretreated once with the alginate and once with the galactomannan preparation. The aim of the study was to determine whether the proposed preparation is suitable for printing polyamide with reactive dyes and which preparation is more suitable for printing the cotton-polyamide blend. The CIE L*a*b* colour values, the colour depth (K/S) and the dye penetration of the printed samples were compared. It was determined that under the same printing conditions, the highest colour depth was achieved on cotton, while a lower depth was recorded on polyamide. The colour depth on the cotton-polyamide blend was lower than on the two pure fabrics. For some colours, the colour depth was higher with the alginate thickener preparation, for others with the galactomannan thickener, so that no definitive preference for one preparation over the other can be given for printing blends. The colour fastness of the prints to dry rubbing (crock test), light and washing at 40 °C was acceptable for all samples.