WOOD RESEARCH Volume 65, Number 1, 2020
Juraj Gigac, Mária Fišerová, Maroš Kováč, and Monika Stankovská

Paper substrates for inkjet printing of uhf rfid antennas

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.

WOOD RESEARCH Volume 66, Number 1, 2021
Juraj Gigac, Mária Fišerová, and Svetozár Hegyi

Comparison of thermal transfer and inkjet printing of UHF RFID tag antennas on paper substrates

UHF RFID printed antennas on conventional and experimentally coated papers by thermal transfer and inkjet technique were not conductive due to high surface roughness. Reducing the surface roughness of paper and hence the electrical resistance of the antennas printed by thermal transfer and inkjet printing was achieved by coating and subsequent calendering process. Papers for thermal transfer and inkjet printed of aluminum and silver antennas were prepared by coating with top functional coating, whose main component was pigment – precipitated calcium carbonate with addition of polyvinyl alcohol, cationic polymer PDADMAC and glyoxal. The desired quality of inkjet-printed silver antennas was achieved by using coated paper with a polyvinyl alcohol barrier layer and a top functional hydrophilic layer. Silver nanoparticles of inkjet ink require a sintering process to obtain a conductive printed trace. The microstructure and thickness of antennas printed by thermal transfer and inkjet technique were compared. Thermal transfer printing created a more homogeneous antenna with greater sharpness of drawing compared to inkjet printing.