Date of Award

8-2012

Degree Name

Master of Science

Department

Chemical and Paper Engineering

First Advisor

Dr. Margaret K. Joyce

Second Advisor

Dave Smith

Third Advisor

Dr. Paul D. Fleming

Keywords

Coating, ink setting, offset printing, deltack, sheet-fed offset

Access Setting

Masters Thesis-Open Access

Abstract

Much attention has been paid to the study of quickset ink setting as a complex ink-coating interaction. Offset ink setting rates are typically measured as ink splitting forces versus time and the slope of the regression line obtained from a plot of these measured values is reported, but scant attention has been paid to the deviations from that straight line. An initial slow ink setting rate is desired to minimize back-trap mottle, carryover picking and piling and enhance ink gloss; then a faster ink setting rate during sheet delivery to the pile is desired to reduce the likelihood of ink set-off, marking and scuffing and to increase product turn around efficiency.

In this work, the relationship between coating structure and the slope of the rising ink setting curve was examined. Coatings of different binder levels, binder polarity and carbonates with different particle sizes were applied to a commercial wood containing paper, using a cylindrical laboratory coater. The coating structures of the coated samples were characterized using mercury porosimetry and surface energy measurements. The Deltack force-time curves were then mapped out for each coating in time intervals small enough to detect inflections within 3s. This novel interpretation of ink setting provides fresh insights into the ink setting process.

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