Dryer Section Simulator for Laboratory Investigations of Shrinkage Profile

摘要

Shrinkage profiles of paper of various geometries were investigated. To do this, a Dryer section simulator was designed using IR-drying on clamped paper to imitate a single free open draw. This condition can be assumed to prevail in a dryer section with a single free draw in which all drying and shrinkage takes place. The results show that it is the in-plane boundary conditions and the geometry of the free draw that is the origin of the shrinkage profile. The higher width to length ratio of the free draw, the lower was the shrinkage in the middle of the sample. The longer length of the sample the steeper was the edge gradient. The possibility to study the influence of papermaking variables was demonstrated by changing the anisotropy of the paper. A drastically decreased anisotropy gave much more uniform shrinkage profile by lower edge shrinkage and increased mid position shrinkage.