ANISOTROPY OF LASER PAPER

Paper runnability in the laser copying and printing processes depends on the in-plane and out-of-plane dimensional changes induced by the ho t fuser roll. These in turn depend on the anisotropic hydroexpansivity of paper The author argues that the anisotropy of wood-free laser pap er web is determined by the fiber orientation and CD drying shrinkage profiles of the paper webs and shows how these properties affect paper performance, in particular stack lean and diagonal curl. The CD-varia tions are usually quite strong and in order to control laser paper run nability one must measure and characterize paper anisotropy over the e ntire web width. The methods developed at KCL for this purpose are des cribed.