複写機内の紙のヒートカール挙動に関する研究 （第１報）

Abstract

Dimensional stability, especially paper curl is one of the most important properties of paper. Paper curl caused by heatroller heating in copymachines and laserprinters, influences the runnability and the end quality of paper. Recently, curl specifications have become more stringent as the development of hardware has progressed. In this study, we made a heatroller heating apparatus with variable heating conditions to investigate the relationship between different heating conditions and the resulting curl behavior. The apparatus utilizes a high pressure nip with one high temperature roll and one low temperature roll to induce non-uniform heating of the paper.Results of this paper show that the curl behavior induced by heatroller heating is influenced by different heating conditions, such as heating temperature, heating speed, and nip width. There is a direct relationship between heating time and paper curl, however, this relationship is affected greatly by changes in the pre-heated moisture content of the sheet. All of these factors have a large influence on how much moisture is lost during the heating process. When the reduction of moisture content is small, curl toward heated side occurs. On the other hand, when the reduction of moisture content is large, curl toward unheated side occurs. The roll nip restrains paper shrinkage in direction of roll pivot, thus the direction in which the paper is feed influences the curl axis. This is useful knowledge when designing a grade of paper where curl is an important property.