No abstract

Conventional papers are not suitable for printed electronics because they have a rougher surface than the plastic film commonly used for electronics printing. The paper surfaces were modified by coating and calendering processes to reduce surface roughness and electrical resistance of inkjet-printed UHF RFID antennas. The composition of coatings, the main component which included aluminum oxide pigment, had an influence on the surface roughness, the surface pore content and the electrical resistance of the inkjet-printed UHF RFID antennas on coated papers. Papers coated with a mixture containing 25% polyvinyl alcohol binder in combination with the cationic polymer PDADMAC without glyoxal crosslinker had the lowest surface roughnesses and the lowest electrical resistances of the inkjet-printed antennas. As the coating basis weight increased, the electrical resistance of the antennas increased. Reduction of the electrical resistance of the antennas was achieved after calendering coated paper. The design of the antennas had a significant effect on their electrical resistance, which increased with the length of the antenna.

The properties of bleached softwood and hardwood kraft pulps at different drainage resistance were compared. Bleached softwood kraft pulps required twice as long time as bleached hardwood kraft pulps, in laboratory beating, to achieve the same drainage resistance. The softwood pulp from a mixture of pine and spruce had the highest dry and wet tensile strength, which was slightly lower than the tensile strength of the pine pulp. The birch pulps had higher dry and wet tensile strength than the pulps from eucalyptus and beech. The bleached softwood kraft pulps had higher fibre strength and fibre length than the hardwood kraft pulps, whose fibres had a higher fibre bonding ability. The water absorption and bulk softness of the bleached hardwood kraft pulps were higher in comparison with those of softwood kraft pulps. The highest water absorption had the bleached kraft pulps from eucalyptus and beech, while the pulps from birch had the highest bulk softness. The bleached hardwood kraft pulps with high bulk softness were characterized by low optical surface variability, while the softwood pulps with low bulk softness had high optical surface variability. Among the tested bleached kraft pulps, the birch and beech pulps had higher brightness than the pulps from eucalyptus, pine and the mixture of pine and spruce. Pulp beating increases the tensile strength, while reducing the water absorption, bulk softness and brightness. Therefore, it is recommended to beat the pulp for tissue paper production to achieve only low drainage resistance, which depends on the type of tissue paper products.

An evaluation of a series of commercial uncoated, semimatte, and glossy coated woodfree papers for the multicolor sheet-fed offset press is presented. This study is aimed at better understanding of mutual influences of surface free energy, paper surface roughness, and fountain solution on print mottling occurring in full-scale printing conditions. Each paper has unique structure in terms of surface roughness, porosity, and surface energy that are the result of manufacturing technology. At the point of contact of liquid with paper, the surface dynamic process of liquid absorption by paper occurs, involving phenomena such as wetting, penetration, diffusion, and swelling. Mottling of colored surface printed by cyan, magenta, yellow, and black inks copied the surface roughness of coated paper. Mottling in the second, third, and fourth printing units showed deviation from mottling in the first printing unit, depending on surface free energy of paper and on the frequency of paper-surface wetting by fountain solution before and after printing.

The influence of surface-applied original and enzymatically-modified sugar beet pectin on strength properties of fluting, coating base paper, and core board was investigated. The effect was compared with the application of commercial strength-increasing agents. With increasing the polymer uptake, measured strength of paper increased. Original sugar beet pectin increased the strength properties of papers, at the same uptake of polymer, to a higher extent than oxidised potato starch or modified grain flour, while the effect of enzymatically-modified sugar beet pectin was the lowest. For the same increase of paper strength, a several times higher uptake of enzymatically-modified sugar beet pectin was required when compared with the original pectin, oxidised potato starch, or modified grain flour.