Characterization of Paperboard Formation using Soft X-radiography and Image Analysis, PaperCon 2016

The in-plane distribution of mass, or paper formation, of paperboard products is a critical property that influences strength properties, cockle and curl, as well as the surface uniformity and print quality. While generating the uniform distribution of fibers in the forming section is of paramount importance, imaging and subsequent analysis of the web structure has been difficult. Few formation analysis systems have sufficient beam energy to penetrate paperboards that have grammages values exceeding 120 g·m-2 with sufficient sensitivity to determine mass variation at the spatial dimensions useful for characterizing the flocked structures. The most common laboratory instrument that is used to map formation in paperboards uses a point sources of 147Pm β-radioisotope with sufficient energy to penetrate boards up to 350 g·m-2. In seeking a more precise imaging method with a higher spatial dynamic range, we investigated the use of 6 keV soft X-radiography with both film and storage phosphor screens to obtain images paper formation within a 70 mm square region of interest. While the soft X-radiography of paper was first introduced 60 years ago by Lambot [1], advancements in X-ray cabinet design and computational power have inspired the reconsideration of this approach. Beam artifacts and low image contrast can now be readily addressed by contemporary image processing of large data sets that can have spatial resolution to less than 10 microns.

This presentation describes the acquisition method for soft X-radiography that enables the capture of images suitable for advanced statistical and spectral formation analysis. One can discern individual fibers throughout the board struc-ture with the high sensitivity and depth of field when film and scanner are used. The use of storage phosphor systems as the image detector enables the rapid imaging at more practical resolutions of interest to board manufacture. The ash content must be considered in order to avoid over estimation of the grammage by this method. An empirical approach that corrects for the presence of inorganic matter is presented. The results suggest that X-radiography is viable for imaging paperboard formation and that it may also be used to examine the size and distribution of internally contained mineral matter.

TAPPI conference proceedings and presentations, technical papers, and publication articles provide technical and management data and solutions on topics covering the Pulp, Paper, Tissue, Corrugated Packaging, Flexible Packaging, Nanotechnology and Converting Industries.

Simply select the quantity, add to your cart and your conference paper, presentation or article will be available for immediate download.