engleski

The impact of inorganic acids on colour stability of digital prints made on substrates with wheat pulp

Agriculture residues are one of the most abundantly available resources worldwide as millions of tons are produced globally. Wheat is a particularly cultivated species in Croatia, and after each harvest, huge amounts of straw remain in the fields. Efficient utilization of this residue to produce paper as a printing substrate offers advantages as reducing the use of primary wood fibres and thus reducing deforestation. In this research, printing substrates with wheat straw will be evaluated in terms of chemical stability of digital prints influenced by inorganic acids. For that purpose, printing substrates were formed on the Rapid Köthen device from pulp obtained by blending different proportions of wheat pulp and pulp of recycled fibres. Colour prints (C+M, M+Y, C+Y and C+M+Y) were made in full tone by digital printing technique and prints were treated with two inorganic acids under the conditions defined in the international standard ISO 2836:2004. Based on the measured spectrophotometric values of the untreated and acid-treated prints, changes in colorimetric values of L*a*b* and the Euclidean colour difference (ΔE00*) were calculated, and the colour stability of prints was assessed. Based on the obtained results it could be concluded that wheat pulp in printing substrates ensures equal or even better colour stability of prints than pulp from recycled fibres.

colour stability, digital prints, inorganic acids, wheat pulp

This work has been supported in part by Croatian Science Foundation under the project „Printability, quality and utilization of substrates with non-wood fibres“ (UIP-2017-05-2573).