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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.

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.