Sung Jai Jeon

Date of Award

8-2002

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Chemical Engineering

Advisor

Douglas W. Bousfield

Second Committee Member

Adriaan R.P. van Heiningen

Third Committee Member

Joseph S. Aspler

Abstract

Paper gloss and print gloss have long been the subject of research because of their strong influence on end-use performance such as image clarity, contrast, and resolution. This work focuses on the significance of the structural factors of porous coatings on print gloss development in a systematic way to elucidate the governing mechanisms. The coating roughness, porosity, and pore size were the three experimental variables. Generation of well defined model coating structures was a challenge and required the appropriate combinations of pigment, binder, and calendering conditions. Calendering techniques with rough substrates (polyester films) were found to produce various rough surfaces without compromising pore structure. Pore structures were controlled during the calendering process by adjusting general calendering parameters. Mercury porosimetry with compressibility corrections was used to evaluate the pore structure of model coatings. Roughness and porosity affect the print gloss from the start moment of evolution indicating their influence on ink transfer and/or ink-film splitting. Once ink film start to level, roughness and pore size determine the level of print gloss in short time (around 10 sec) after the printing nip, while that of porosity controls the evolution of print gloss in time. The major structural factors exert significant effects on print gloss development independently based on the exclusive relations. The effects of the structural factors are consistent overall though there is mild leveling off in extreme conditions, in which other phenomenon such as splitting pattern may also involve in the print gloss development. Inking amount did increase the print gloss generally but did not alter the trends within a given range. Finally, this work highlights the result of a quantitative systematic response of print gloss for the structural factors. Roughness is found to be the most important factor overall followed by pore size and porosity, respectively. The order of main effects is consistent in the low paper gloss region. However, in the high paper gloss region, pore size becomes more important than others. The results suggest that the similar effects may involve in print gloss mottle and other related properties.

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