Effect of paper and printing press variables on the rates of adhesion failure in the linting of offset printing

Abstract

Lint problems occur when loosely bonded particles detach from the surface of uncoated paper and accumulate on the printing blanket. We investigated the effect of paper and the printing press variables of printing tone and ink tack on linting using a lint camera system and also by stopping the press repeatedly to wash the lint samples off the blanket. Lint particles were classified into small particles (with area 0–8000 μm²) and large particles (with area above 8000 μm²). There have been many contradictory reports about the most important paper and printing variables affecting linting because many previous researchers have not adequately addressed that linting is a dynamic process, which involves two adhesion failures and separations, driven by the splitting of the viscous ink film. The first failure is for the removal of lint particles from the paper surface to the blanket, while the second failure is for the separation of the lint particles from the blanket. The key finding of this study is that these two rates of adhesion failure are generally correlated. That is, a higher rate of lint particle separation from the paper surface is associated with a higher rate of separation from the blanket. This finding held for varying the grade of paper, the ink viscosity and the printing tone, and for small and large particles. Previous contradictory results from linting studies are because lint has only been measured after completing a printing trial, with no means of examining the two underlying adhesion failure processes.

Keywords:

• linting
• offset printing
• printing tone
• ink tack
• adhesion failure

Acknowledgements

We would like to acknowledge Grant Brennan for his assistance with the sheet-fed printing trials. Rosiana Lestiani would also like to thank the financial support from the Australian Research Linkage (ARC) LP0989823, Norske Skog and Monash University.