Screen Printing with Natural Dye Extract from Japanese Knotweed Rhizome.

Excessive overgrowth of an invasive alien plant like Japanese knotweed is an ecological problem that threatens the ecosystem and reduces biodiversity. However, it can be potentially used for various beneficial purposes, e.g. for the production of paper or natural dyes, as a renewable and sustainable resource. In our research, the orange extract of the Japanese knotweed rhizome was used as a natural dye for the formulation of screen printing inks. The prepared printing inks with different dye concentrations were printed by flat screen printing technique on two papers made of Japanese knotweed stem and on two commercial papers as well as on cotton and polyester fabrics. The color of the prints was evaluated spectrophotometrically and the fastness of the printing inks on different printing materials was analyzed. The research results confirmed the usefulness of the natural dye derived from the Japanese knotweed rhizome for printing, especially on papers whose prints showed very good rub resistance. However, its application for printing on textiles is limited due to its lower fastness to wet treatments such as washing, wet rubbing, and wet ironing. The natural dye is resistant to fading under the influence of light, but its color becomes darker. When exposed to light, yellow prints darken to orange-brown prints, which are more pronounced at higher dye concentrations; however, this could be an interesting effect on printed products. [ABSTRACT FROM AUTHOR]