The development of an ultrasonic measurement for the prediction of paper strength properties - Part 2.

摘要

Following the successful development of ultrasonic techniques for the measurement of in-plane paper properties work has been undertaken to map, in detail, the strength variability of current commercially produced packaging papers. A commercial paper was measured using a new in-plane testing technology and the ultrasonic measurements were related to ring crush measurements using proprietary algorithms that show high correlation and give good confidence to the sonic estimates. Z-direction measurements (thickness direction) were also made using a technique developed by IPST in the 1980's and 1990's and the position of the thickness-direction measurement was matched to the position of the in-plane measurement. In this way overlapping mappings in all three principal paper directions - MD, CD and ZD have been generated. Studies show that the variability associated with in-plane shear stiffness in the plane of the sheet can also be presented. From these three dimensional mappings a theoretical mechanism for the observed property variability is suggested and new measures for controlling overall packaging board quality are proposed. The impact of the scale and magnitude of variation in commercial paper compression strength properties, such as CD ring crush, is also discussed in terms of packaging field performance under various conditions.