Effect of the cushioning properties on runnability and print quality for offset printing of newsprint paper

Abstract:

Newsprint paper is required to have excellent runnability on the offset print press, because it is printed in large quantities with a quite high speed at a time to keep the strict delivery time in Japan. Therefore, it is necessary to control many kinds of paper properties that are related to the runnability on the offset print press. We have known that the cushioning properties of paper have some relations to runnability and print quality experientially, but there have not been appropriate methods to evaluate it and the adequate study has not been done on their effects.
In this study, it was found that the behavior of the newsprint paper during the compression along z-direction was well expressed by the compressive stiffness and the stress relaxation (cushioning property) obtained from the compression test. We evaluated the behavior about handmade sheets from various kinds of pulps. It was found that KP had high compressibility and high cushioning, meanwhile, TMP had high compressibility and poor cushioning. And also, the composition of pulp and the manufacturing condition clearly affected the compressive stiffness and stress relaxation, and well-cushioned newsprint paper had a good print quality with good ink receptivity.
In this paper, we will present a new method which can evaluate the cushioning properties of paper using compressive stiffness tester and the effects of the cushioning properties on the print quality of newsprint paper.