Rheological properties of printing pastes and their influence on quality-determining parameters in screen printing of cotton with reactive dyes using recycled polysaccharide thickeners

Alginate, carboxymethylated guar gum and carboxymethylated cellulose, used as thickeners in printing pastes for monoreactive dyes, were recycled from wastewater concentrates (separated by ultrafiltration from wastewater after screen printing of cotton), and from printing paste residues (obtained from the cleaning of printing equipment and application systems in the printing machine). The printing performance, using original and recycled polymers, was studied via rheological properties of printing pastes and quality-determining parameters of printing. A quantitative interpretation of the flow and the viscoelastic properties, which are strongly connected to the qualitative parameters of printing, was obtained using rheological models (Cross and Friedrich–Braun model). Recycled thickeners are easily reused for screen printing of cotton with monoreactive dyes, provided that the printing paste recipe fits a rheological constraint of equal viscosity in the steady shear conditions.