The effects of coating colours on base papers

Purpose The purpose of this paper is to investigate the influences of coating colours and their contents on the fundamental properties of base papers and also evaluate these results in terms of mechanical and wood-free papers. Design/methodology/approach A design research approach has been based on the application of various coating colours and analysis of mechanical and optical tests results of the coated mechanical and wood-free base papers. Findings This study is confirmed that the coating colours can be easily applied to the surface of the papers. The experimental data have revealed that significant improvements exist in the values of tear resistance (strength), brightness and opacity of the mechanical base papers, especially by the application of the coating colours including kaolin pigment. The results show that mechanical papers can also be used in areas with high brightness expectations by applying coating colour. Originality/value The originality of this work is based on understanding and comparing the effects of applying similar coating formulations on mechanical and wood-free base papers.

Sensitization rate and sum of sige-antibodies to apple grades of various colours. Association of these indices with severity of atopic dermatitis

Aim. To assess the rate of sensitization to the grades of apples of various colours and analyze the association of the obtained indices and total sIgE levels of these grades with the severity of atopic dermatitis. Materials and methods. The blood sera of 215 patients, suffering from alimentary allergy, were studied. The detection rate of sensitization and that of specific immunoglobulin E (sIgE) concentration sum to allergens of apple grades with various coating colours as well as the association of these indices with the degree of severity of atopic dermatitis (AD) was analyzed. Test-systems were used for immune-enzyme analysis of production. Statistical analysis of the obtained results was performed using the program “MedStat” (Donetsk). Results. It was shown that the detection rate of sensitization to the grades with mixed red colour is reliably higher (p < 0.001) compared to the grades without coating colour. The degree of AD severity correlates with the total quantity of apple grades, to which sensitization has been revealed (p < 0.01), with the quantity of grades with mixed red colour, to which sensitization has been found (p < 0.01) and with sIgE sum to the grades with mixed red colour (p < 0.01). Reliable differences (p = 0.006) in the degree of severity of atopic dermatitis among persons, sensitized to apple grades and with no sensitization to this fruit were established. Conclusions.The obtained data are to be used when choosing a diet and correcting it for persons with alimentary allergy and atopic dermatitis.

Comparing the rheological properties of novel nanofibrillar cellulose-formulated pigment coating colours with those using traditional thickener

Nanocellulose containing materials, such as micro-fibrillated cellulose (MFC) and nanofibrillated cellulose (NFC), are potential additives which could improve strength properties of coated paper and board surfaces and thus substitute natural and synthetic cobinders, such as carboxymethyl cellulose (CMC) and polyacrylic thickeners, in pigmented coating formulations. The aim of this study is to evaluate whether MFC/NFC can be used in coating colours as sole co-binder. In this investigation, the change of rheological and dewatering behaviour of coating colours, having a single blend of pigments (ground calcium carbonate and kaolin clay) together with a latex emulsion binder, is studied when CMC is used as sole co-binder and during its partial and finally total replacement with MFC/NFC. The findings suggest that even though all coatings show viscoelasticity, MFC/NFC is seen to relate to the gel-like nature of the nanoparticles in the coating colour whereas the viscoelastic behaviour in the case of CMC is induced by differential flocculation amongst the pigment and latex binder. The flocculation mechanism is predicted to be necessary in order to provide the link between water retention and elastic structure recovery where anti-sagging is a prerequisite, such as in the coating of rough substrates, e.g. for board and packaging.

Fractal Analysis of Coated Papers

The main goal of this research is to apply AFM to the analysis of coated paper topography in order to find out relationships between sheet gloss and some parameters obtained from AFM, such as roughness and fractal dimension (D). Flooding technique was also developed using appropriated software. Number of hills/flooding volume for 25%, 50% and 75% flooded volume was applied in this research. Ground calcium carbonate and precipitated calcium carbonate were applied in coating colour formulations, alone and blended in three formulations, 75:25, 50:50 and 25:75. The results obtained showed high correlations between sheet gloss with fractal dimension (D) parameter. Finally, flooding technique showed to be very interesting, all of them gave useful information in interpreting the influence of topography on sheet gloss.

Relating ink solvent-coating component thermal properties to smearing and development of abrasion resistance in ink jet printing

The target of this study was to identify the interactions of the compounds of printing ink and paper coating colour and their effects on the inkjet print quality. Interactions between inkjet ink solvent components and their interaction with paper coating compounds are considered significant for the final print quality. Especially, ink solvent properties play an important role in inkjet ink drying. The methods used to study these interactions are thermogravimetry (TGA) and differential scanning calorimetry (DSC), and results are analysed for correlations with print quality. The experimental material consists of both commercial and model inkjet inks, paper coating colour compounds and commercial papers. To visualize the thermal data and to combine the TGA and DSC measurements in a single plot, a representation has been used, in which the specific gravimetric (TGA) and specific energy (DSC) ratios, m1/m2 and E1/E2, corresponding to the mass loss and energy consumed per unit mass of sample, in the temperature regions T < 100°C and 100°C < T < 220°C, respectively, are plotted against each other. The determined ratios differed greatly between different model solvents and ink series. The thermal behaviour of the solvents is seen to be relevant for predicting inkjet print quality.