Method of applying protective device on the surface above perforation in paper machine

摘要

A sheet material (110) having a security device (112) applied over a paper machine made or 'soft-edged' through-hole (111) and a method for preparing such a sheet material (110) is provided. By way of the inventive method, the through-hole(s) is formed in a forming fibrous web before it becomes sufficiently consolidated and then the security device is applied onto the fibrous web and preferably over the through-hole(s) at or near a couch roll or similar tool of a paper machine when the fibrous web constitutes a sufficiently consolidated, fully formed wet web. Applying the security device and then further consolidating the region underlying the device at this stage of paper manufacture when the fibers would not be displaced, greatly reduces (if not eliminates) the possibility of the through-hole(s) becoming occluded or blocked. Moreover, papers made in accordance with the inventive method, when subjected to the Circulation Simulation Test, showed minimal damage at the paper/security device interface. Further, the surface-applied security devices showed acceptable levels of intaglio ink adhesion, and the papers had higher cross-direction (CD) tensile strength and much less show-through on opposing sides thereof.