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Packaging and labels are used for a variety of products and have become an indispensable part of daily life, while products without labels or packaging cause uncertainty among consumers. The global trend is to reduce the amount of packaging waste by recycling and reusing the same material or using other available waste raw materials. With large quantities of stalks remaining discarded in the fields after harvest each year, cereal straw is emerging as an alternative source of lignocellulosic fibers for secondary green packaging and labels. In this study, the usability of printed papers with discarded lignocellulosic fibers by offset and gravure printing processes for secondary green packaging and labels was observed based on the qualitative parameters of reproduction and ink penetration into the printing substrate. From the obtained results, it can be concluded that gravure prints have greater penetration of the ink into the printing substrate, resulting in more uneven surface coverage with printing ink, compared to offset prints, where the viscosity of the ink and the printing process itself have the greatest influence. Therefore, these substrates with discarded lignocellulosic fibers can be used for secondary green packaging and labeling printed by the offset printing process, while gravure printing requires an additional coating or a larger amount of filler in the paper structure.

Even though most information is digitized today, paper as a printing substrate is still essential. The quality of the paper depends on whether it has the properties required for its intended use, which will fundamentally rely on the raw materials used. Nowadays, the production of paper and board is increasingly focused on alternative non-wood raw materials. In this context, the main objective of this research is to improve the quality of prints on laboratory-made papers with supplementary barley pulp by coating the surface of the papers with titanium dioxide coating. Since laboratory-made papers were not subjected to the bleaching process and no additional surface treatments were used, TiO2-based coating proved to be one of the ways to improve the quality of the prints on such substrates. In this study, it was concluded that TiO2-based coating did not affect the colorimetric values of the black prints to the extent that it affected the colorimetric values of the magenta prints. However, density of printed inks was increased up to 14% for prints on laboratory-made papers with higher amount of barley pulp and TiO2-based coating in two layers.

Today the print quality of digital printing techniques has improved and is considered satisfactory and competitive to analogue techniques for certain graphic products. Satisfactory print quality mostly depends on the interaction of ink and printing substrate where ink penetration has an important role. Namely, the ink penetration affects the parameters that describe the print quality together with visual appearance of print density and mottling. Therefore, it is important to select an adequate printing substrate for each printing technique. Awareness of environmental problems related to the shortage of wood raw materials has led to an increase in the use of recycled printing paper and in particular the implementation of new alternative sources of cellulose fibres instead of virgin wood fibres in the papermaking process. In this research the emphasis is precisely on defining the influence of ink penetration into laboratory papers made of triticale pulp on the final print quality. The laboratory printing papers were obtained by mixing triticale pulp with pulp from recycled fibres in three different portions. Papers were thereafter printed by ultraviolet (UV) inkjet printer and the ink penetration within laboratory papers with and without straw pulp was analysed using two methods of ink penetration analysis (microscopic/spectroscopic). The influence of ink penetration on the final print quality was observed and analysed based on several quality parameters (optical ink density, mottling and colorimetric values). These results confirmed that triticale pulp in laboratory papers provides equal print quality compared to laboratory papers made only from pulp from recycled fibres.

Surface characteristics of printing substrates are of the utmost importance to all types of paper that interact with ink. During all types of printing processes, the behaviour of the liquid phase (ink or dye) on the paper is directly defined by the paper cellulose-based surface. The printed ink spreads and penetrates more into paper fibres when the paper surface is rougher and more permeable. Contact angle measurements by sessile drop method are considered the most appropriate for determining the paper sheet surface energy. Paper as hydrophilic material has a high absorption rate resulting in a low contact angle. The objective of this study was to evaluate the surface free energy of laboratory-made papers containing straw pulp obtained from residues after the harvest of the most cultivated cereals in Croatia (wheat, barley and triticale). The obtained surface free energy results are promising for straw pulp usage in the manufacture of printing paper.

From the moment of production, paper as a printing substrate is exposed to the process of natural ageing regardless of the type of cellulose fibres in its composition. Accordingly, the prints produced by the various printing techniques are also exposed to several factors that impair the quality of the print i.e. its colour over time. Therefore, it is very important to properly select the printing substrate for achieving a high quality of graphic products. For that purpose, three types of papers with hemp fibres were used as printing substrates which were printed with laboratory hand-operated instrument Esiproof using flexographic cyan (C), magenta (M), yellow (Y) and black (K) water-based inks. Prints were artificially aged in SunTEST XLS+ test chamber according to standard ASTM D 6789-02 for 48 and 96 hours. Based on changes in the reflectance spectra of each printed ink after exposure to electromagnetic radiation it was noticed how composition of printing substrate strongly influence on colour stability of prints due time. An increase of exposure time to electromagnetic radiation leads to a decrease in the value of the reflectance of the printing substrate and cyan, magenta and yellow prints. It was confirmed how electromagnetic radiation have the greatest impact on the reflectance of yellow print, while the black one is the most stabile regardless of the substrate it was printed on.

Natural ageing has a major influence on the properties of paper, while light, heat, and humidity are the environmental influences that most disrupt the stability of paper. This research focuses on changes in straw-containing papers caused by accelerated ageing. The papers were made in the laboratory by mixing straw pulp with the pulp of recycled fibers in different weight ratios and were artificially aged by a dry-heat treatment (thermal oxidation) and UV radiation treatment (photo-oxidation) over a 24 h period to simulate natural ageing. The observed changes in the optical, surface, and chemical stability of papers were analyzed and are discussed in this paper. It is evident that, regardless of the origin of straw for pulp production, it forms papers that undergoes similar optical properties (photo-yellowing and brightness lose), while certain differences have been observed in surface and chemical stability. Based on all analyses performed as part of this research, it was found that paper produced with the addition of wheat pulp is the most stable of all laboratory straw-containing papers. However, it must be emphasized that, if lignin-containing straw pulp is used as the main constituent of paper, the brightness stability of such pulp must be improved, or the paper surface must be improved by surface finishing in order to obtain greater stability against ageing.

Considering that optical properties play a very important role in the printing industry, this research focused on analysing the optical properties (opacity, whiteness, brightness and yellowness) of laboratory made papers from recycled wood pulp, with the addition of different straw contents, coated with titanium dioxide white ink. Titanium dioxide white ink was applied on laboratory papers to achieve optical characteristics as those of commercial papers recommended by ISO 12647. All the coated laboratory papers presented whiteness within the recommendations of the standard. Almost all the coated papers made with the addition of straw pulp achieved satisfactory optical properties, especially those containing 10% and 20% straw pulp. Coated laboratory papers containing 10% and 20% wheat pulp were comparable to commercial paper and reached a similar value of brightness, while their opacity and yellowness values were even better than those of commercial paper. In order to preserve the natural appearance of papers made with the addition of straw pulp, it is possible to conduct selective white printing as background for high-quality printing.

Today, the paper industry is faced with a global deficiency of raw wood materials, so alternative sources of virgin cellulose fibres are playing an important role in paper production. Agricultural countries produce large quantities of crop farming by-products such as straw, which is an interesting alternative raw material for cellulose fibres. Straw is used in many industries because of its numerous advantages: animal food industry, biofuel industry, construction industry and as artistic material. The potential use of straw production residues is of great importance in paper and printing industry. The focus of this research is on triticale straw, which was used as a non-wood fibre source for paper production. Namely, triticale straw was converted into semi-chemical pulp and was combined with recycled wood pulp in order to produce alternative laboratory papers. The usability of this kind of laboratory papers in printing industry was analysed based on line reproduction quality. This research evaluated and analysed line reproduction quality based on four line attributes: width, blurriness and raggedness. The results of this research proved that triticale pulp in laboratory papers has equal influence on line printing quality as the recycled wood pulp.

This research observes changes in the properties of commercially available hemp office papers exposed to photo-oxidation for artificial aging. In order to accelerate the changes that naturally occur in paper, photo-oxidation was performed using a Xenon light source. The electromagnetic radiation was administered in doses of 550 W/m2 over 24 hours with a temperature of 60°C. Three types of hemp office papers that differ in chemical composition and manufacturing process were used as samples. The strength properties (tensile index, elongation at break, tear index), surface properties (Bendtsen roughness, Bekk smoothness), pH of paper extracts, and optical properties were observed. The listed properties of artificially aged samples were compared to those of unaged commercial paper samples. The results show that, after only 24 hours, accelerated aging with a Xenon arc lamp affects all observed paper properties. For all analyzed office papers, the values of the tensile index, Bekk smoothness, and pH of paper extracts decreased, while the values of elongation break, tear index, and Bendtsen roughness increased due accelerated aging. Regarding the CIE L*a*b* color space value, lightness (L*) generally decreased after the aging treatment, and all paper samples became less reddish (a* decreased) and more yellow (b* increased). The obtained results of this research reveal that pulp with hemp fibers can produce higher-quality office paper that is more stable against light and temperature influences than those made with post-consumer fibers. However, to increase the durability of manufactured paper, hemp fibers must be bleached.

As newsprints, mostly made from recycled wood pulp, are not high quality papers according to its optical, mechanical and chemical characteristics, in this research the usage of straw pulp as an alternative raw material was analyzed. For that purpose, straw pulp was mixed with recycled wood pulp and strength properties of laboratory made papers were determined according to TAPPI standards. Selection of agricultural waste for preparing straw pulp was based on annual yield of crop species (Triticum spp., Hordeum vulgare L. and Triticale sp.). Results indicated that straw pulp can be efficiently used in portions up to 20% as a substitute for wood fibers or as an additive in order to obtain particular newsprint properties.

The objective of the research was to investigate colorimetric changes of the waterbased flexographic ink printed on hemp-based papers subjected to artificial ageing. Three types of commercially available hemp office papers were used as printing substrate and by Esiproof instrument were printed manually in full tone with process waterbased flexographic inks. Both, papers and prints were exposed to artificial ageing in the Suntest XLS+ test chamber according ASTM D 6789-2 standard. The L∗, a∗, b∗ colour coordinates were measured and ΔE00 colour difference was calculated for different stages of light exposure in order to determine the change from the original color value. In total exposure time was 96 h. The results have shown how the paper optical stability is dependent upon manufacturing process and that bleached hemp fibers provides better optical stability of papers than unbleached hemp fibers. Further, stability of prints made on hemp-based papers is for the most part defined by ink color, while the impact of the printing substrate is less pronounced. Generally, it was noticed how the most stable among prints were prints covered with the black ink, while prints with the yellow ink had the greatest changes in color under the influence of light.

Paper performance qualities strongly depend on the origin of cellulose fibers. Awareness of environmental issues and sustainable development has led to the increase in the use of recycled printing papers. Recovered fibers are often used as a substitute for virgin wood fibers in the production of certain types of papers. As recovered fibers cannot provide the same quality level of paper products as virgin wood fibers, alternative sources of virgin cellulose fibers need to be identified. The aim of this research was to analyze the printability of laboratory papers made of different contents of straw pulp. Therefore, the printing papers were formed using straw pulp of three different cereal species (wheat, barley, and triticale) and mixing them with recycled newsprint in different weight ratios. The printability of these laboratory papers was analyzed by classifying dot reproduction quality based on four dot reproduction attributes. Printed dot reproduction greatly affects the quality of reproduction in graphic products, as dots are the most important element in multi-color reproduction of texts and images. It was confirmed that laboratory papers containing straw pulp provide the same or even better dot reproduction quality than laboratory control papers formed only of recycled newsprint.

This research observes alteration in optical properties of two commercially available hemp office papers exposed to various methods of accelerated ageing. Both handmade office papers, natural colored and non-chlorine bleached were formed from 100% hemp plant fiber. In order to establish their optical stability under controlled conditions two different accelerating ageing treatments were carried out for the period of 24 hours as a simulation of different degradation processes that naturally occurs in cellulosic materials: thermal oxidation (TO) and photo-oxidation (PO). Before and after ageing treatments the changes in the optical properties of papers were monitored by X-rite DTP 20 spectrophotometer and obtained differences in Reflectance index (R), Euclidean difference (ΔE00*) and Yellowness Index (YI E313) have been discussed. The results have shown how the paper optical stability is dependent upon manufacturing process. Namely, it was found that bleached hemp pulp provide better optical stability of papers than unbleached hemp pulp.

For paper industry and consequently graphic industry it is very important that fibres used in paper production provide high quality and printability of the paper. In pulp and paper industry fibres of cellulose pulp derived still predominantly from wood, but in the last few years the consumption of non-wood raw materials for that purpose has grown. This work presents research on the chemical stability of printed hemp fibre based papers to water, alcohol and alkali. Evaluation of chemical degradation on prints was determined through the spectro-photometric measurements. Deviations in colour of prints have shown that highest chemical stability provides prints made on industrially paper formed from mixture of hemp and post-consumer fibres with high share of inorganic components. Further, bleached hemp fibres in handmade 100 % hemp fibre based paper give prints with the lowest chemical stability.

Wood is still the most widely used raw material for pulp and paper production in the world. However, due to the necessity to supply the paper industry with raw materials used in the extraction of cellulose fibres and the overexploitation of forests, new sources of primary pulp fibres had to be identified. The aim of this research is to highlight the important features of cereal crop residues and their utilization in the paper industry. As the chemical composition of plant materials is one of the most important indicators of how such materials can be used in paper production, the analysis of the chemical composition of straw with the highest grain production was performed. The straw, as a harvesting residue, is a fibre resource available from the annually renewable crops, produced abundantly in numerous regions all over the world. For the purpose of the research, wheat, triticale and barley straw were selected for the analysis. The analysis of carbohydrate, lignin and extraneous material (organic extractives and inorganic minerals) was performed in order to obtain the straw chemical composition. Based on the results of the chemical composition of all analysed straw, it was confi rmed that straw, as an agricultural by-product, is rich in cellulosic fibres and, therefore, a valuable raw material for the paper industry. Out of all analysed straw, based on the results of their chemical composition, triticale straw is considered potentially the best source of alternative cellulose fibres.

Wood is still the most widely used raw material for pulp and paper production in the world. However, due to the necessity to supply the paper industry with raw materials used in the extraction of cellulose fibres and the overexploitation of forests, new sources of primary pulp fibres had to be identified. The aim of this research is to highlight the important features of cereal crop residues and their utilization in the paper industry. As the chemical composition of plant materials is one of the most important indicators of how such materials can be used in paper production, the analysis of the chemical composition of straw with the highest grain production was performed. The straw, as a harvesting residue, is a fibre resource available from the annually renewable crops, produced abundantly in numerous regions all over the world. For the purpose of the research, wheat, triticale and barley straw were selected for the analysis. The analysis of carbohydrate, lignin and extraneous material (organic extractives and inorganic minerals) was performed in order to obtain the straw chemical composition. Based on the results of the chemical composition of all analysed straw, it was confi rmed that straw, as an agricultural by-product, is rich in cellulosic fi bres and, therefore, a valuable raw material for the paper industry. Out of all analysed straw, based on the results of their chemical composition, triticale straw is considered potentially the best source of alternative cellulose fibres., Drvo je još uvijek najčešća sirovina za proizvodnju celuloze i papira u svijetu. Međutim, s obzirom na količinu sirovine za izdvajanje celuloznih vlakanaca potrebnih papirnoj industriji te na prekomjernu eksploataciju šuma, nužno je pronaći nove izvore primarnih celuloznih vlakanca. Cilj ovog istraživanja bio je istaknuti važnost slame koja je kao poljoprivredni ostatak prikladna sirovina za industriju papira. Kako je kemijski sastav biljnog materijala jedan od najvažnijih razloga njegove upotrebe u proizvodnji papira, određen je kemijski sastav slame žitarica s najvećim doprinosom zrna. Slama, kao ostatak nakon žetve, godišnje je obnovljiv izvor vlakanaca u mnogim regijama diljem svijeta proizvodi u izobilju. Za ovo je istraživanje izabrana slama pšenice, pšenoraži i ječma. Obavljena je kvantitativna analiza ugljikohidrata, lignina i ekstraktivnih tvari (organski ekstrakti i anorganski minerali) kako bi se odredio kemijski sastav slame žitarica. Na temelju kemijskog sastava svih analiziranih slama potvrđeno je kako je slama kao poljoprivredni nusproizvod bogat izvor celuloznih vlakanaca, a time i vrijedna sirovina za industriju papira. Od svih analiziranih uzoraka slama pšenoraži svojim se kemijskim sastavom nametnula kao najveći potencijalni izvor alternativnih celuloznih vlakanaca.

This paper describes the improved removal of impurities (coating, ink/toner) from offset prints produced by digital printing of two-side coated paper. The substrates were printed by conventional and digital offset processes. Based on image analysis results it was established that deinking flotation is an inefficient method for ink particle removal from digital offset printed paper, but it is efficient for ink removal from conventional offset printed paper. On the other hand, pre-treatment with hydrogen peroxide solution gives better results for ink particle removal from digital offset prints than from conventional offset prints. Optimal parameters for hydrogen peroxide pre-treatment for both offset prints were chosen based on unprinted substrate mass loss results in the preliminary investigation. These results showed that hydrogen peroxide pre-treatment is more successful at removal of impurities in comparison with flotation deinking without pre-treatment.

This paper presents the examination of effects of amphoteric surface active chemical cocamidopropyl betaine (CAPB) on the optical properties of various office paper brands (Navigator, Fabriano, Rcopy, Pioneer, IQ and Plano Premium). In order to analyse the effects of cocamidopropyl betaine on the office papers’ optical stability, two types of sample treatments were performed: Soaking and disintegration. Likewise, for the purpose of better optical stability evaluation, the same analysis was done with distilled water. All paper samples were exposed before and after treatment to visible and ultraviolet electromagnetic radiation. The influence of ultraviolet radiation on all treated office papers was examined through reflectance spectra using X-rite Spectrophotometer. The gained results showed that cocamidopropyl betaine affected optical properties of all analysed office papers, independently of the type of treatment, compared to non-treated originals. It was evident that the degree of surfactant solution effect on the optical stability was conditioned by paper composition.