Dimensional Stability and Curl of Paper (I)

Abstract

A large number of studies on the factors affecting the dimensional stability and curl of paper, and their mechanism have been carried out to date from the physical viewpoint, and they have given us nearly all phases of fundamental knowledge on the problem. However, arrival at a solution to curl in the mill site by applying these theoretical studies is not easy. Papermakers have tried to solve the problem and are often in a difficulty in the mill because too many factors are involved in the papermaking process, which add to the two-sidedness of the sheet. Antagonistic and/or synergistic interactions of these factors vary according to each mill depending upon the papermaking conditions employed, and these interactions sometimes lead papermaking engineers to take wrong actions. Thus, it is difficult to find a solution to curl problems.
Under these circumstances, this paper deals with theoretical studies on curl by summarizing the works of W. Gally, A. Tydeman and so on. It is imperative to understand their theories in order to find a remedy to the problem in the mill site.
This paper also introduces three reports on actual papermaking experiences on curl, and finally presents the author's own theory and proposal to eliminate the curl of paper.