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Utjecaj anorganskih kiselina na stabilnost obojenja digitalnih otisaka na podlogama s pšeničnom pulpom The impact of inorganic acids on colour stability of digital prints made on substrates with wheat pulp Ivana Plazonić, Irena Bates, Valentina Radić Seleš, Maja Rudolf, Katja Petric Maretić, Mihael Jergović Sveučilište u Zagrebu Grafički fakultet Sažetak Poljoprivredni ostaci jedan su od najrasprostranjenijih svjetskih resursa jer se milijuni tona proizvode globalno. Pšenica je najviše uzgajana vrsta u Hrvatskoj, a nakon svake žetve na poljima ostaje ogromna količina slame. Učinkovita upotreba slame za proizvodnju papira kao tiskovne podloge nudi prednosti poput smanjenja upotrebe primarnih drvenih vlakana i smanjenja krčenja šuma. U ovom će se istraživanju tiskovne podloge s dodatkom pšenične pulpe evaluirati s obzirom na kemijsku stabilnost digitalnih otisaka pod utjecajem anorganskih kiselina. U tu svrhu na uređaju Rapid Köthen načinjene su tiskovne podloge od pulpe dobivene miješanjem različitih udjela pšenične pulpe i pulpe recikliranih vlakana. Otisci (C+M, M+Y, C+Y i C+M+Y) su izrađeni u punom tonu digitalnom tehnikom tiska te su tretirani s dvije anorganske kiseline pod uvjetima definiranim u međunarodnoj normi ISO 2836: 2004. Na temelju izmjerenih spektrofotometrijskih vrijednosti netretiranih i kiselinom tretiranih otisaka izračunate su promjene kolorimetrijskih vrijednosti L*a*b* i Euklidske razlike u boji (ΔE00*) te je procijenjena stabilnost obojenja otisaka. Na temelju dobivenih rezultata može se zaključiti da pšenična pulpa u tiskovnim podlogama osigurava jednaku ili čak bolju stabilnost boje otisaka nego pulpa iz recikliranih drvnih vlakanaca. Abstract 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 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 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. ivana.plazonic@grf.unizg.hr
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