engleski

Spectroscopic and microscopic methods in the analysis of ink jet prints

The aim of the study was to verify the application of spectroscopic and microscopic methods in the testing of stability of Ink-Jet prints. The methods used were Raman spectroscopy, Confocal laser scanning microscopy, Fourier Tranform infrared photoacoustic spectroscopy and UV resonance Raman spectroscopy. The tested samples were printed with dye and pigment inks on different printing substrates: Ink-Jet photopaper, coated coartonboard, uncoated permanent paper and tissue paper. Materials were analysed before printing: droplet formation was subjected to image analysis in order to gain information about the droplet area, perimeter and circularity. The depth profiles obtained from the Raman spectra show the dominant components of the prints. They represent the vertical ink distribution in the print up to the depth of 40µ m. The CLSM method scans the horizontal levels of the measured area of the print. It enables the orthogonal projections of virtual cross-sections from each point of the scanned area. The measured ink layers correlate with those from the Raman depth profiles. The FTIR-PAS collects the signal from the depth of 5 - 10µ m and does not register the upper ink layer of the print. This method does not register the presence of the ink at the measured depth, the collected signal reflects the paper components only. The UVR Raman spectroscopy collects the signal from the very surface of the print. The intensities of the spectra correlate with the depths of the compact ink layer as defined by the CLSM method. Control measurements were done by the destructive methods of sample preparation followed by microscopy. The SEM was used on cross-section images and LM on the microtome images of the prints. These measurements confirmed the insights into the ink distribution obtained by non-destructive methods.

Raman spectroscopy; CLSM; UV R Raman; FTIR-PAS; SEM; Microtome sections

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