New Method to determine Pigment Friability: example - scalenohedral PCC, PaperCon 2016

Achieving mechanical strength of structured pigments under compression or strain is an important factor in the control of compaction and dusting, which in turn manifest themselves in increased density and as a quality issue in respect to handling, printing and converting, and environmental cleanliness. Dusting can also lead to a reduction in the longevity of trimmers and cutters. Precipitated calcium carbonate (PCC) is commonly used primarily as a filler in the paper and board manufacturing industry, and examples of clustered or structured morphology find application as optical and bulk enhancers in both filling and coating. However, these very properties, depending on the structural morphology of PCC, can make it prone to mechanical weakness and dusting. The potential of using a replacement stronger PCC of similar particle size distribution is that it would compact and dust less. A novel method is reported here for measuring the friability of pigment samples, exemplified in this work using bulky scalenohedral PCCs of similar particle size, by applying a range of pressure to compress the dry pigment in a powder compact. Mercury porosimetry is used to determine the change in pore structure and how the change relates to the compression applied. Constructing a mathematical relation specifically between the change in pore size and the change in pore volume it is possible to define a friability index. The method is intended to be used, for example, pre-trial, to help give an idea about compaction and potential dusting in relation to pigment friability, and thus limit potentially unnecessary costly trials for the papermaker and pigment supplier in both filling and coating. Correlation between calendering compaction from an idealised coated layer and experimentally determined friability is also investigated.

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.