The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Forest Products Technology for public examination and debate in Auditorium V1 at Helsinki University of Technology (Espoo, Finland) on the 22nd of October, 2004, at 12 o'clock noon.
Overview in PDF format (ISBN 951-22-7231-8) [1391 KB]
Dissertation is also available in print (ISBN 951-22-7230-X)
In offset printing on coated papers an uneven print, mottling, is a serious problem. Uneven styrene-butadiene (SB) latex distribution may be the reason for the mottled print. In this work, confocal Raman microscopy methods were developed for chemical and physical characterization of printed and coated papers. The main emphasis was laid on analysis of the SB-latex distribution in x-y-z direction.
A depth profiling method was developed. An immersion method was found to be essential in the depth profiling of light scattering coated papers. Model samples were employed to obtain a better understanding of the depth profiling method. The method was applied in the analysis of SB-latex migration and measurement of the thickness of paper coating layers and ink films.
Lateral mapping of paper coatings was developed for bulk and surface analysis. In mapping of coating bulk, the whole coating layer was measured and the analysis could be done through print. Lateral mapping of the bulk layer provided information on SB-latex distribution, and variations in coat weight and ink density could be mapped simultaneously. Bulk mapping was combined with light microscopy images acquired from the same area.
A higher magnification objective gave the means to measure the outermost 1-2 µm of the coating layer. Analysis of the coating surface is important because of the ink–coating interaction taking place on the coating surface. In the surface analysis, SB-latex content and its variation in different scales were of interest. The total areas analysed contained many areas of 1 mm × 1 mm.
This thesis consists of an overview and of the following 4 publications:
Keywords: Raman, depth profiling, immersion, mapping, coating, binder, migration
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© 2004 Helsinki University of Technology