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Aglomeracija delcev v premazni mešanici se izkazuje kot nezaželen učinek in ima negativen vpliv na končni izdelek premazanega papirja. Vsak osnovni papir, ki pride iz papirnega stroja, ima naravno reliefno strukturo površine, ki je neenakomerna in groba. Če mu želimo izboljšati površinske lastnosti, mu je na površino treba dodati premaz. Papir ali karton premazujemo z različnimi premaznimi mešanicami. Slednje so sestavljene iz pigmentov, veziv, koveziv, pomožnih sredstev in vode. V premaznih mešanicah se delci med seboj povezujejo v večje skupke oz. aglomerate. Aglomeracija kalcijevega karbonata kot pigmenta je negativni pojav vseh disperznih sistemov, ki se mu ni moč izogniti in predstavlja neposredni rezultat medsebojnega učinkovanja dispegiranih delcev in tekočine, kar vpliva na mikrostrukturo papirja. Zaradi neenakomernega tvorjenja aglomeratov po površini je ta na mikro ravni še vedno nekoliko hrapava, hrapavost pa je učinek, katerega vpliv si želimo s premazovanjem zmanjšati in poskusiti površino narediti bolj gladko. Smisel premazovanja papirja je tvorjenje bolj enakomerne površine, s čimer se izboljša potiskljivost oz. tiskovne lastnosti. Slednje vpliva predvsem na izboljšanje površinskih in optičnih lastnosti, kot so gladkost, sijaj, belina, neprosojnost, enakomernost površine, kakovost tiska, enakomerno navzemanje tiskarske barve in sposobnost lakiranja. Namen magistrskega dela je bil preučiti vpliv različnih sestav receptur premaznih mešanic in kako le-te vplivajo na stopnjo aglomeracije kalcijevega karbonata, kakšna je vloga veziv, katera komponenta v največji meri prispeva k zniževanju oz. zviševanju stopnje aglomeracije ter ugotoviti, kako ustrezna je v raziskavo zajeta fizikalno-mehanska metoda zmanjševanja stopnje aglomeracije s pomočjo ultrazvoka. Z raziskavo smo preučevali lastnosti premazanih papirjev, tj. osnovne, površinske, strukturne in optične lastnosti, in s slikovno analizo preko elektronskega vrstičnega mikroskopa (SEM) pridobili podrobnejši vpogled v mikro dogajanje sestavnih delov premaznih mešanic, ki jih v svojem proizvodnem procesu uporablja Papirnica Vevče. Preučevanih je bilo 6 različnih vzorcev, z različno vsebovanostjo kalcijevega karbonata in kaolina. Vzorce smo v nadaljevanju razdelili v 3 sklope, tj. glede na namen obdelave. To so bili vzorci premazanih mešanic, vzorci premaznih mešanic, ki so bili obdelani z ultrazvokom 5 min pri temperaturi 35 °C in vzorce obdelane z ultrazvokom 5 min pri temperaturi 45 °C. Rezultati so pokazali, da je bila aglomeracija višja pri vzorcih, ki so vsebovali večji delež CaCO3 glede na sklop vzorcev z večjim deležem kaolina. Kalcijev karbonat dosega najvišje vrednosti hrapavosti, poroznosti, togosti in zrcalnega sijaja. K večji aglomeraciji so delno pripomogla tudi veziva in sprememba temperature. Fizikalno-mehansko obdelovanje z ultrazvokom ne more v zadostni meri premagati kemijskega privlaka med pigmentnimi delci, kar rezultira v delni aglomeraciji. Večji aglomerati so se sicer razbili na manjše, zmanjšala se je tudi velikost pigmentnih delcev CaCO3 in kaolina, vendar ultrazvok ni izničil pojava aglomeracije. Agglomeration of particles in the coating mixture is an undesirable effect and has a negative impact on the final coated paper product. Each base paper coming out of the paper machine has a natural embossed structure which is uneven and rough. If we want to improve its surface characteristics, it is necessary to add a coating to the surface of the paper. Paper or cardboard is coated with different coating mixtures. These consist pigments, binders, metal binders, auxiliaries and water. In coating mixtures, the particles are connected together to form larger aggregates or agglomerates. Agglomeration of calcium carbonate as a pigment is an unavoidable negative process of all dispersions and is a direct result of the interaction between the dispersed particles and the liquid, which affects the microstructure of the paper. The uneven formation of agglomerates on the surface still results in a slightly rough surface on micro level, and roughness is an effect whose impact we want to reduce by coating the paper and try to make the surface smoother. The purpose of coating the paper and making the surface as even as possible is to improve its printability or its printability characteristics. This mainly affects on the improvement of surface and optical properties such as smoothness, gloss, whiteness, opacity, surface uniformity, print quality, uniform ink uptake and the abičity to varnish. The aim of the MSc thesis was to study how different coating formulations affect on the level of agglomeration of calcium carbonate, what is the role of binders, which component contributes the most to reducing or increasing the level of agglomeration, and to determine how suitable is the physico-mechanical method of reducing the level of agglomeration by ultrasonication. Trough research we studied the properties of the coated papers (basic, surface, structural and optical properties) and trough image analysis using a scanning electron microscope (SEM), obtained a more detailed insight into the micro-evolution of the components of the coating mixtures used by Papirnica Vevče in its production process. Six different samples with different contents of calcium carbonate and kaolin were studied. The samples were further divided into 3 sets according to the purpose of the treatment. These were samples of coated mixtures, samples of coated mixtures treated by ultrasonication for 5 min at 35 °C and samples treated by ultrasonication for 5 min at 45 °C. The results showed that agglomeration was higher in samples containing a higher proportion of CaCO3 compared to the set of samples with a higher proportion of kaolin. Calcium carbonate has the highest values of roughness, porosity, stiffness and gloss. The higher agglomeration is partly due to the binder and the change in temperature. Physico-mechanical treatment with ultrasound cannot sufficiently overcome the chemical attraction between the pigment particles, resulting in partial agglomeration. Although the larger agglomerates were broken down into smaller ones and the size of the pigment particles CaCO3 and kaolin was reduced, ultrasound did not cancel the agglomeration process.

Introduction The barrier properties of paper-based packaging may not be sufficient for long-term storage to ensure the quality and taste of packaged food products. All this requires researching the technological features and developing a combined packaging material in which the base paper is combined with polymer materials or a metallized coating is applied to its surface. Results and discussion Food products are very sensitive to the influence of external factors, so the barrier properties of paper-based packaging become insufficient for long-term storage to ensure the quality of food products and their taste properties. All this requires the development and mastery of the production of modern barrier combined packaging materials and conducting research on the development of requirements for base paper in order to obtain combined, namely: metallized packaging materials. As research results have shown, base paper should be characterized by high resistance to mechanical influences in the process of processing, as well as exploitation of the finished material. It should have a surface that provides optimal interaction with the foil, have high barrier and protective properties. In the process of carrying out research on the creation of a new combined package, the requirements for the metallized material and the quality of the base paper were determined. The index of smoothness of the surface of the base paper should not be lower than 150 s, and its moisture content should not exceed 4%, because its higher values, as experiments have shown, do not allow creating the necessary rarefaction in the chamber for metallization and ensuring the uniformity of metal application. In the case of spraying aluminum with increased residual humidity of the paper, intensive oxidation processes take place, which negatively affect the quality of the coating, its protective properties and the strength of adhesion (adhesion) to the surface of the substrate. As a result of the research, graphical dependences of the electrical resistance and opacity of the metallized material on the thickness of the coating were also obtained, which plays an important role in improving the protective, barrier and other properties of the packaging. Experimental data were also obtained that illustrate the influence of the speed of rewinding and the smoothness of the surface of the base paper in the process of metallization in a vacuum on the indicator of electrical resistance, which is an indirect characteristic of the thickness of the metallized coating of the material. The conducted studies of the new combined metallized packaging material also showed that the coating contributes to the improvement of the protective properties of the material and the tightness of the packaging, namely: reducing gas permeability, weakening the effect of optical radiation on products, increasing the opacity and smoothness of the surface. Conclusions New packaging materials created in the course of research - paper with a metallized coating can be used in packaging processes., Не існує універсального пакувального матеріалу, разом з тим, харчові продукти дуже чутливі до впливу зовнішніх факторів. Тому бар'єрні властивості упаковки на основі одного паперу за тривалих термінів зберігання стають недостатніми для забезпечення якості та смакових властивостей харчових продуктів. Все це вимагає дослідити технологічні особливості та розробити комбінований пакувальний матеріал, в якому папір поєднується із полімерними матеріалами або на його поверхню наносять металізоване покриття.

Four major toners are used in the printing industry, cyan, magenta, yellow and black (Key) for making color images on paper. Paper brands suitable for printing have thin mineral/latex coatings, and toners are applied on top of the coating in the printing process. Chemical compositions from toner to toner, as well as from coating to coating, vary according to the needs of the end user. Interactions between the toner and the coating define the final color formation of the images in printing. Hence, it is important to study characteristics and dynamics of toners on coated papers. In this paper, we have used laser-induced plasma spectroscopy (LIBS) to provide information on elemental distributions of the toner and the coating layers on three coated papers and the base paper at a sub-micrometer resolution. Ablation crater depth profiles in the three different material layers were converted into metric scale by combining elemental information from the LIBS measurements and optical profilometry. Ablation efficiencies for a toner of 150 nm/pulse, for a coating of approximately 350 nm/pulse and for a base paper of approximately 1 μm at a fluence of 0.6 J/cm2 of an ArF excimer laser were determined. Using these results, the average layer thicknesses of the toner and the coating layers were evaluated. The detailed analysis of the elemental profiles of the two cyan toners studied revealed strong accumulation of silicon and titanium compounds of the toner on the toner–air interface but also on the toner–coating interface, but to a much smaller extent. The observation reveals the significance of toner component diffusion due to substrate–machine interaction in the printing process. Such diffusion processes must have an important role in final color formation of the images in printing. The method developed provides a unique and accurate means to study toner diffusion processes in coated papers under printing conditions.

In this study, the effects of the lacquer applied to the printing materials which were printed by electrophotographic printing method on printing quality were investigated. In practice, printing materials with the same weight and different optical properties were used and the study was carried out in three stages. The optical and physical properties of the printing materials used in the first part were determined, in the second part, the printing of these materials by electrophotographic printing method and printability tests were performed. In the third chapter, matte and glossy lacquers were applied to these printed materials and printability tests were repeated. As a result of the study, it was observed that the application of gloss and matte lacquer caused a decrease in the printing density values and also the application of matte lacquer caused a decrease in the gloss values.

Nanofibrillated films based on TEMPO-oxidized cotton linters were applied to reduce the hydrophilic properties of paper. For this purpose, aqueous dispersions of nanofibrillated cellulose of different composition: 1 and 3% of nanofibrillated cellulose, up to 13% of CaCO3 and/or Al(OH)3, up to 20% of propane-1,2-diol (glycol), and up to 21% of TEMPO-oxidized cotton linters were coated on the model paper, without additional adhesive. The pristine model paper and papers coated with nanofibrillated cellulose-based composite films were characterized in terms of water absorptiveness by COBB method and water drop contact angle measurements. The surface appearance was characterized by scanning electron microscopy (SEM) and surface chemistry by infrared spectroscopy with Fourier transform and attenuated total reflection (ATR-FTIR). Additionally, optical properties, i.e. measurement of reflection curves and CIE degrees of whiteness, were determined according to appropriate standards. For all papers coated with nanofibrillated cellulose-based films, depending on the composition of the dispersions, a decrease in sorption properties was achieved, without changes in optical properties and surface morphology of the paper compared to the pristine paper.

There is a pressing need around the world to develop novel functional biodegradable materials to separate oil/water mixtures and emulsions completely. Recently, superhydrophilicity and underwater superoleophobicity materials have been attracted attention due to their high efficiency in oil/water separation. However, it is still a challenge to prepare materials that combine oil/water separation and water purification in an environment-friendly way. In this work, biodegradable starch-based nanospheres (SNPs) coated filter paper was prepared in a low-cost, simple, and environmentally friendly manner. The SNPs coating could not only help to change the wettability of the substrate material but also build the hierarchical micro and nano structures which are conducive to separation and purification process. After modification by coating SNPs, the filter paper exhibited excellent performance in a wide range of oil/water mixtures or emulsions separation and the wettability of the filter paper could be regulated by adjusting the pH value. The modified filter paper presented good recyclability after several separation process. Furthermore, the as-prepared filter paper could also remove water-soluble contaminants during the oil/water separation process, thus realizing to combine separation and purification process in one single step. This biodegradable starch-based separating material with good separation performance, stability and recyclability has significant application potential in practical separation and purification process.

Starch and derivatives thereof have proven their usefulness in paper coating processes. Among these derivatives, cationic starch has been widely used in the paper industry as a flocculation, dispersion and ink fixing agent. In another context, nanoscale cellulosic materials have been shown to improve the strength, retention of fillers, the barrier properties of packaging paper products, and printing qualities. This review summarizes the recent studies on the general components used in paper coating, describes the conventional and alternative synthetic processes of cationic starches and nanocellulose, and deals with their current and potential applications in papermaking, focusing primarily on surface treatments. Moreover, environmental applications have been considered to expand the understanding and usefulness of these materials. Further research on modified polysaccharides is encouraged to replace, in a feasible way, petro-based components of coating formulations, and to provide paper surfaces with new properties.

Application of barrier dispersion coatings on paperboards, which must have proper moisture and grease resistance for food applications, has always been an interesting subject for the packaging industry. In this study, paperboards were coated with a novel dispersion barrier coating prepared through mixing soy protein isolate (SPI) and polyethylene wax (PE-wax). Different characterization methods were used to study the effects of coating and its composition on the physical, mechanical, and barrier characteristics of paperboards. The results indicated that the incorporation of PE-wax into the coating formulation caused significant reduction of the viscosity of coating slurries. It had no effect on the coating weight of the samples but increased the thickness of the coated paperboards as compared with those coated with SPI only. The increase of the wax content led to a reduction of 5-16% in the tensile strength values in comparison with the uncoated paperboards. Barrier characteristics, i.e., water vapor permeability (WVP), surface wettability, and water resistance, improved by adding PE-wax. In addition, it was found that there was a critical level for the addition of PE-wax, 50% of SPI, as no oil migration was detected when the paperboards coated with SPI coatings contained less than 50% PE-wax.

A soft body area sensor network presents a promising direction in wearable devices to integrate on-body sensors for physiological signal monitoring and flexible printed circuit boards (FPCBs) for signal conditioning/readout and wireless transmission. However, its realization currently relies on various sophisticated fabrication approaches such as lithography or direct printing on a carrier substrate before attaching to the body. Here, we report a universal fabrication scheme to enable printing and room-temperature sintering of the metal nanoparticle on paper/fabric for FPCBs and directly on the human skin for on-body sensors with a novel sintering aid layer. Consisting of polyvinyl alcohol (PVA) paste and nanoadditives in the water, the sintering aid layer reduces the sintering temperature. Together with the significantly decreased surface roughness, it allows for the integration of a submicron-thick conductive pattern with enhanced electromechanical performance. Various on-body sensors integrated with an FPCB to detect health conditions illustrate a system-level example.

Paper derived from lignocellulose has great advantages over plastics as packaging material, nevertheless, the poor water- and oil-resistances of paper-derived products limited their application in high-end field. Herein, novel dimer acid-based waterborne polyurethanes (DWPUs) with different content of dimer acid-based polyester polyol (DG) were prepared and used as water- and oil-resistant coating for paper substrate. The effects of DG contents on water- and oil-resistances, mechanical properties and thermal stability of DWPUs coated papers were systematically investigated. When the content of DG reached up to 7 wt% (based on polyester glycol), the paper coated by DWPU exhibited 88.06% decrease in Cobb 60 value, 8.7 times increase in kit rating compared with uncoated paper. Meanwhile, DWPUs coated papers showed good mechanical properties and thermal stability. These improvements are attributed to the flexible long-alkyl chain, and six-ring structure of DWPUs as well as the continuous and homogeneous DWPU-derived membrane on the surface of paper. This study provides a new framework for the preparation of high quality, multifunctional, environmentally friendly water- and oil-resistant coatings for paper substrates.

The use of nanocelluloses is being conducted for the most diverse applications. Their performance as coating agent has been mainly explored to improve barrier properties, as they emerge as perfect candidate for plastic substitution, but it is also important to explore their potential to improve printing quality. In the present work, the influence of different nanocelluloses, obtained through mechanical, enzymatic, TEMPO-mediated oxidation and carboxymethylation treatments, in the coating process and inkjet printability of office papers was assessed. The results revealed that the cellulose nanofibrils are better for printability than the microfibrils. But the size and charge of the former must be taken into account, since fibrils of very small size penetrate the paper structure, dragging the pigments from the surface, and very anionic nanofibrils can also have negative influence on the optical density. Besides, an interesting synergy between surface-sizing starch and the cellulose nanofibrils was found to occur as the latter closed the paper structure, which prevented starch from penetrating, while potentiating both of their positive effects on ink pigment entrapment. An additional study of characterization of inkjet pigments was also performed.

Paper-based packaging is widely employed in industries ranging from food to beverages to pharmaceuticals because of its attractive advantages of biodegradability, recyclability, good strength, low cost, and lightweight. However, paper products usually have poor water barrier resistance properties because of paper and fibers porous microstructure. In this study, an ecofriendly water-resistant (hydrophobic) oil from biological origin, namely, palm kernel oil (PKO) was used to coat paper by using a facile and cost-effective dip-casting approach. PKO formulation was prepared by mixing with a solvent and furfuryl alcohol (FA). The water resistance, structural properties, and thermal and mechanical properties of the coated papers obtained under different processing conditions were reported and compared to understand the performance of coated paper. Contact angle (CA), Fourier transform infrared (FTIR), and thermal gravimetry (TGA) were used for analysis and characterization of coated papers. Data from contact angle measurements showed that the PKO formulation could considerably improve the liquid water barrier property of the paper, with a measured water contact angle (CA) of ∼120° and reduce the water vapor transmission rate (WVTR) by 22%. This novel, green, low-cost, and water-resistant paper coating made with biological and biodegradable oil is a potential candidate for replacing petroleum-based coatings used in a broad range of applications and will also be able to make an additional full use of the palm kernel oil.

Removing benzene from indoor space plays an important role in indoor air purification. A novel filter with vegetal fiber paper (VFP) as matrix hosting silica gel is proposed in this paper for benzene removal. In order to investigate the feasibility and performance of this idea, firstly, three pieces of VFP samples impregnated with different amounts of silica gel are fabricated and their benzene adsorption quantities are tested. The results show that three times is recommended as the optimal number for impregnating. The VFP sample impregnated with silica gel after the third impregnating exhibits commendable coating stability and good benzene adsorption performance. Additionally, at low relative pressure (Pb /Ps ≤ 0.05), the experimental data of benzene adsorption isotherms fit well with the Langmuir model with R2 greater than 0.97. Then, two actual filters made of VFP impregnated with silica gel after the third impregnating were fabricated. It is found that the pressure drop of the actual filter is only 1200 Pa/m when the air velocity is 2 m/s. Besides, the one-pass efficiency of the filter can reach to 19.44%. It is expected that the silica gel coated on the filter can be modified to improve the purification performance of the filter.

A lignin-based PU coating was prepared for paper-based green packaging. Two representative diisocyanate were used to prepare the coatings. Due to the rigid aromatic, the physical properties of the TDI system reached the maximum below the lignin content of 40%. The HDI that contains flexible aliphatic chains alleviated the brittleness of coating, and it showed physical advantages when the lignin content was more than 50%. Owing to the high lignin content, the coating presented enhanced thermal stability. After coated with the lignin-based PU coatings, the dry tensile strength of coated paper was improved by 126%. Amazingly, the wet strength was increased from 0.31 to 12.6 MPa with an improvement nearly 40 times. Based on the coordination of lignin, Ag+ was introduced into the PU matrix, which imparted the coating with excellent antibacterial ability. The colony forming units of E. coli and S. aureus were both less than 1. However, no inhibition halo was observed, which indicated that the Ag was firmly anchored on the coating and the antibacterial ability is only available when the bacterial contact the coating surface. The lignin-based PU coating with favorable sustainability and properties shows great potential in paper-based green packaging fields.

Cellulose is a promising biomass material suitable for high volume applications. Its potential lies in sustainability, which is becoming one of the leading trends in industry. However, there are certain drawbacks of cellulose materials which limit their use, especially their high wettability and low barrier properties, which can be overcome by applying thin coatings. Plasma technologies present a high potential for deposition of thin environmentally friendly and recyclable coatings. In this paper, two different plasma reactors were used for coating two types of cellulose-based substrates with hexamethyldisiloxane (HMDSO). The changes in surface characteristics were measured by atomic force microscopy (AFM), scanning electron microscopy (SEM), surface free energy and contact angles measurements, X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). Successful oleofobization was observed for an industrial scale reactor where pure HMDSO was used in the absence of oxygen.

This paper is aimed at investigating the usage of biosynthesized poly(3-hydroxybutyrate) (P(3-HB)) for a coating on pineapple leaf fiber paper (PLFP). For this purpose, (P(3-HB)) was produced by Rhodococcus pyridinivorans BSRT1-1, a highly potential P(3-HB) producing bacterium, with a weight-average molecular weight (Mw) of 6.07 × 10 −5 g/mol. This biosynthesized P(3-HB) at 7.5% (w/v) was then coated on PLFP through the dip-coating technique with chloroform used as a solvent. The respective coated PLFP showed that P(3-HB) could be well coated all over on the PLFP surface as confirmed by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The brightness and mechanical properties of PLFP could be improved by coating with biosynthesized P(3-HB) in comparison to commercially available P(3-HB) and non-coated PLFP. Furthermore, coating of P(3-HB) significantly increased the water drop penetration time on the surface of PLFP and was similar to that of the commercial P(3-HB) with the same content. The results showed that all the coated PLPF samples can be degraded under the soil burial test conditions. We have demonstrated that the P(3-HB) coated PLFP paper has the ability to prevent water drop penetration and could undergo biodegradation. Taken together, the P(3-HB) coated PLFP can be applied as a promising biodegradable paper packaging.

Replacing synthetic polymers with renewable alternatives is a critical challenge for the packaging industry. This research investigated the use of leaf-based proteins as a sustainable co-binder in the coating formulations for paper-based packaging and other applications. Protein isolates from tobacco leaf and alfalfa concentrates were characterized using the Pierce protein assay, Kjeldahl nitrogen, and gel electrophoresis. The proteins were tested as co-binders in a typical latex-based paper coating formulation. The rheology and water retention properties of the wet coating and the surface, optical, structural, and strength properties of coated papers were measured. The coating performance was affected by the purity, solubility, and molecular weight of the tobacco protein and exhibited a shear-thinning behavior with lower water retention than soy protein. Analysis by scanning electron microscopy and time of flight secondary ion mass spectroscopy on the dried coating layer containing tobacco protein showed enhanced porosity (advantageous for package glueability) relative to the control latex coating. The tobacco protein offers adequate coverage and coating pigment distribution, indicating that this protein can be a suitable option in coatings for packaging applications.

The progress of bio-based fluorescent smart materials and their multifunctional applications have attained increasing interest in the recent decades. Cellulose is among the cheapest and widespread raw material on earth which can be modified into diverse useful materials. This review summarizes the chemical modification of cellulose into smart fluorescent materials. This further highlights on the fabrication of the prepared fluorescent materials into films, fibers, paper strips, carbon dots, hydrogels and solutions which are applied for the sensing of toxic metals and anions, pH, bioimaging, common organic solvents, aliphatic and aromatic amines, nitroaromatics, fluorescent printing, coating, and anti-counterfeiting applications. Finally, the discussion about the upcoming investigations, challenges, and options open for the cellulose-based luminescence sensors are communicated. We believe that this review will appeal more and more attention and curiosity for the chemists, biochemists, and chemical engineers working with the synthesis of cellulose-based fluorescent materials for widespread applications.

Solar-reflective thermal insulating coating (SRC) has received great attention because of its desired heat reflective properties and water repellency, which may impart high-value to cellulosic paper via industrially well-established surface coating process. However, the feasibility and possibility of surface application of SRC to cellulosic paper have not been explored. Herein, in the present work, SRC was designed/developed and subsequently used in the surface application to cellulosic paper. Effect of feeding level of titanium dioxide nanoparticles (nano-TiO2) on rheological behavior of the coating, as well as heat-reflective properties, water repellency and mechanical properties of the surface-coated paper was studied. Results showed that the as-obtained coating samples exhibited a notable shear-thinning behavior and displayed strong dependence of rheological behavior on nano-TiO2 amount. Furthermore, the increased nano-TiO2 amount appeared to induce the improved hemispherical emittance of coated paper. The coating weight was also found to exert a positive effect on the hemispherical emittance of coated paper. In addition, it was confirmed that the nano-TiO2 addition played an important role in improving the water repellency and mechanical properties of coated paper.

A functional biopolymer-coated paper was prepared by coating a ternary blend of the alginate, carboxymethyl cellulose, and carrageenan with grapefruit seed extract (GSE) for the substitute use of synthetic polymer-coated paper. The microstructure of the surface and cross-section of the coated paper analyzed by field emission scanning electron microscope (FE-SEM) indicated that the biopolymer was compatible with the base paper and filled the pores of the porous fiber to make a smooth-surfaced coating paper. The properties of the biopolymer-coated paper, such as water and oil resistance, water vapor barrier, surface hydrophobicity, and mechanical properties, increased significantly compared with not only the base paper but also commercially used PE-coated paper. The blended biopolymer coating material exhibited strong antibacterial activity against food-borne pathogenic bacteria, Listeria monocytogenes and Escherichia coli, which were destroyed completely within 3 and 9 h, respectively. The packaging test for a minced fish cake packed with the biopolymer-coated paper showed the complete destruction of surface inoculated bacteria in 6–9 days. The biopolymer-coated paper showed a high potential for disposable food packaging applications to increase the shelf-life of packaged food.

Paper based sensor is the new technology to fabricate a simple, portable, and low cost device that exhibits the comparable properties and functions with those fabricated using complex fabrication process. Paper based sensor is usually applied in environmental monitoring, health diagnostics, and food quality control. This research is focusing on the paper based sensor that will contribute to the development of Ultraviolet (UV) sensor. The fabrication of the sensor was done by using different grade of pencil, namely 6B and 2B on different type of paper. The different grade of pencil corresponds to different percentage of graphite and clay. As for the type of paper, A4 printing paper and Whatman filter paper were used. UV sensing operation was analyzed from the measurement of current-voltage (I-V) characteristics under the exposure of UV light. Zinc oxide (ZnO) was coated on the sensor to facilitate the detection in the presence of UV. The sample fabricated using 6B pencil grade on A4 printing paper and with ZnO coating showed a better UV sensing performance compared to other samples. This is due to the high conduction of 6B pencil grade and smooth surface of A4 printing paper. The ZnO coating increased the sensor sensitivity and response towards the UV light. These findings provide valuable information which can be used in fabricating a low-cost and simple UV paper sensor.

Pokanje premazov na pregibu je napaka, ki izkazuje negativen vpliv na končni izdelek. Proizvajalci papirja zato stremijo k odpravi pokanja premaza z namenom, da se izognejo reklamacijam in težijo k lastnosti raztezanja premaznega sloja na tiskovnem materialu s sočasno zadostno natezno odpornostjo papirja proti pregibu. Papirjem, ki izkazujejo nizko odpornost proti pregibu se pogosto pretrgajo vlakna in prekinejo medvlakenske povezave njihova natezna odpornost se v primeru premazovanja poveča. Kakovost papirjev je povezana z dolžino in številčnostjo celuloznih vlaken, saj se ta ob pregibu ne pretrgajo, ampak le upognejo. Premazovanje papirjev je dodelavni postopek, pri katerem se izboljšajo optične in tiskovne lastnosti in poslabšajo fizikalno-mehanske lastnosti, kamor uvrščamo tudi prepogibanje papirja. Pokanje premazov je običajno posledica površinske masa surovega papirja, količine premaznega sloja, vplivov posameznih sestavin v premazni mešanici ter zunanjih okoljskih dejavnikov, kot sta temperatura in vlaga. Namen raziskave pokanja premazov specialnih grafičnih papirjev v magistrskem delu, ki je potekalo v sodelovanju s Papirnico Vevče, je bil preučiti lastnosti premazanih papirjev (osnovne, površinske in strukturne lastnosti), primerjava premaznih mešanic glede na njihovo sestavo, prepoznati vplive na pokanje premazov in določitev kombinacije sestavnih delov osnovnega papirja in premaza, ki bi izkazovala najnižjo tendenco pokanja. Preučevanih je bilo 5 različnih vzorcev specialnih grafičnih papirjev, tj. PackPro 7.1 (V1), NiklaPack (V2), Niklaselect (V3), NiklaPET (V4) in PackPro 7.5 (V5). Vsi vzorci so enostransko premazani in primerni za postopek oplemenitve papirja – kaširanje. V1, V2 in V5 so namenjeni izdelavi gibke embalaže, V3 in V4 pa sta namenjena izdelavi etiketnih papirjev. Rezultati raziskave pokanja premazov so pokazali, da ima na tendenco pokanja znaten vpliv debelina papirja in z njo posledično količina premaznega sloja. Vpliv je bil zaznan tudi zaradi višje količine vsebnosti vlage v vzorcu. Korelacija med tendenco pokanja premazov in sestavinami premazne mešanice je bila najbolj opazna pri vsebnosti višje količine veziv in izbrane vrste le-teh. The cracking of coatings on the fold is a defect that harms the final product. Therefore, paper manufacturers strive to eliminate coating cracking to avoid complaints or objections and strive to achieve the elongation properties of the coating layer on the substrate while, at the same time, providing sufficient paper tensile strength against creasing. With papers with low crease-resistance, the fibers often tear and thus break the fiber bonds. Their tensile strength increases with the coating. The quality of the paper depends on the length and frequency of the cellulose fibers, since they do not break when folded, but only bend. The coating of paper is a finishing process in which the optical and printing properties are improved but the physical and mechanical properties are deteriorated, which includes folding the paper. Cracking during coating is usually due to the surface mass of the base paper, the number of coating layers, the effects of the individual components in the coating mixture, and external environmental factors, such as temperature and humidity. The aim of the investigations on cracking in coatings of special graphic papers in the master thesis which was carried out in cooperation with Papirnica Vevče was to investigate the properties of coated papers (base, surface, and structural properties), to compare coating mixtures according to their composition, to identify effects on cracking of coatings, and to determine combinations of base paper and coating components that would have the lowest tendency to crack. Five different samples of special graphic papers were examined, i.e. PackPro 7.1 (V1), NiklaPack (V2), Niklaselect (V3), NiklaPET (V4), and PackPro 7.5 (V5). All samples are coated on one side and suitable for the paper finishing process – laminating. V1, V2, and V5 are intended for the production of flexible packaging and V3 and V4 for the production of label papers. The results of the study on coating cracking showed that the tendency to cracking is significantly influenced by the thickness of the paper and consequently by the number of coating layers. The effect was also determined due to the higher moisture content in the sample. The correlation between the tendency to coat cracking and the components of the coating mix was most evident in the content of a higher amount of binders and the selected binder types.

In the present work, a facile and green synthesis approach for the production of monodispersed, small-sized (2.9 ± 0.7 nm) and stable silver nanoparticles (AgNPs) using soluble soybean polysaccharide (SSPS) was reported. SSPS was used as the reducing and stabilizing agent. The obtained SSPS-stabilized AgNPs (SA) were characterized by UV–vis absorption spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The antimicrobial activity of the SA colloidal dispersion (SACD) was evaluated based on the growth kinetics of bacteria E. coli and S. aureus. Afterwards, the colloidal dispersion was applied as a coating material to Kraft paper. The SACD-coated Kraft paper exhibited excellent antimicrobial activity against above bacteria strains and P. aeruginosa. The effects of SACD coating on surface wettability, barrier property and microstructure of the Kraft paper were also studied. The results suggested that the SSPS-stabilized AgNPs have great potential in antibacterial applications.

A paper-based platform was developed and tested for studies on basic cell culture, material biocompatibility, and activity of pharmaceuticals in order to provide a reliable, robust and low-cost cell study platform. It is based upon a paper or paperboard support, with a nanostructured latex coating to provide an enhanced cell growth and sufficient barrier properties. Wetting is limited to regions of interest using a flexographically printed hydrophobic polydimethylsiloxane layer with circular non-print areas. The nanostructured coating can be substituted for another coating of interest, or the regions of interest functionalized with a material to be studied. The platform is fully up-scalable, being produced with roll-to-roll rod coating, flexographic and inkjet printing methods. Results show that the platform efficiency is comparable to multi-well plates in colorimetric assays in three separate studies: a cell culture study, a biocompatibility study, and a drug screening study. The color intensity is quantified by using a common office scanner or an imaging device and the data is analyzed by a custom computer software without the need for expensive screening or analysis equipment.

Chitosan with low (25 kDa) and high molecular weight (2100 kDa) were used to enhance performances of paper made from steam-exploded bamboo fibers and nanofibrillated cellulose. Chitosan solutions with concentrations of 0–1.0 wt% were manually applied on paper surface using a facile coating approach with a wire bar. Effects of chitosan coatings on morphology, thermal stability, wettability, mechanical performances and antibacterial properties of the paper were investigated. The larger improvement in the mechanical properties and wettability of the chitosan coated paper was observed with increasing concentrations of chitosan due to the disappearance of empty pores between fibers within a cellulose network by the formed chitosan matrix. These improvements were significantly higher when high molecular weight chitosan was applied. Yet, the addition of chitosan slightly decreased the thermal stability of the coated paper, and the chitosan coating did not improve the antimicrobial properties of the paper. The antimicrobial activity of chitosan against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) was found to be diminished when a chitosan solution was entrapped within paper. Together with the overall migration of the paper in food simulants, the results suggested that the chitosan coated paper could be applied for non-food-direct-contact packaging materials.