Print uniformity of corrugated board in flexo printing: effects of corrugated board and halftone dot deformations

Abstract

Print non-uniformity is a major concern for fl exo post-printers. Many of these nonuniformities are suspected to be caused by the corrugated board structure itself. Striping is the most obvious one, but also other print quality problems might be structure-related. This work focuses on how deformations of the board might lead to print non-uniformities, and if the deformation of halftone dots is the mechanism behind striping in halftone fl exo post-printing. Finite element models were used to analyse the effects of deformations of corrugated boards and compressed halftone dots in the printing nip. Distortions of the board due to non-uniform hygro-thermal strains were shown to be a potential cause of print non-uniformities. Striping in halftone prints was found to be caused by differences in dot gain between areas above ridges and valleys of the fl ute structure.

Post-Printing of Colored QR Code on Corrugated board Packages in the Egyptian Printing Industry

“…• Second: for the patches which were prepared to be printed as halftone process colors not as spot or special colors: 1-The patches No. 5,6,9,11,13,14,15,16 ,17, 18, 19 and 20, were read correctly and very quickly and from all angles from the first time, however they were printed in halftone structure, for two reasons: first, because of keeping the printing parameters specially color registration in its high accuracy level for getting a high quality printing for the QR codes to be very close to the ones that printed in a spot color structure, Second, because they make a high contrast difference between them and the brown background, it ranges between 60% to 76% (see table 4). 2-The patches No.…”

Enhancement of flexographic print quality on bleached kraft liner using nano-silica from rice husk

“…dot area = 0%) to the area where it is fully printed (dot area = 100%) [42]. When pressure from the printer is exerted, the dot expands on the printing surface, causing changes in the tonal values [43].…”