Digital inkjet dyeing and printing of textiles with vat dyes

The well-established commercial inkjet ink formulations for cellulosic textile fibres commonly make use of reactive dyes. Cellulosic fibres are also dyed and screen printed commercially with vat dyes, especially for high performance and technical applications. However, inkjet printing with vat dyes remains problematic. Within the EC Framework 6 integrated project DIGITEX, Digital Fast Patterned Microdisposal of Fluids for Multifunctional Protective Textiles, we have developed an inkjet system for digital dyeing and printing of cotton using solubilised vat dyes. Aqueous-based inkjet inks using solubilised vat dyes have been developed with appropriate physical and theological characteristics providing good jettability during printing on to cellulosic fibres. Dye purification and judicious additive selection to minimise premature formation of the vat dye and consequent reduced ink storage stability were essential to produce high quality inkjet inks. With these formulations, and with appropriate optimised fabric post-treatment, inkjet vat dyeings and prints on cotton may be produced with a high standard of technical performance.