Characterization of “Stickies” Polymeric Contaminants in Recycle Pulp Slurries by Optical Fluorescence and Scanning Electron Microscopy.

Extract

A major problem now hampering increased recycling of old cardboard containers (OCC), is the presence of significant amounts of polymeric materials such as adhesives, tapes, labels and wax which enter the pulp process stream along with the cardboard and paper that was collected for recycling. Many of these materials contain very fine particles of inorganic fillers and pigments. These various contaminant constituents combine in some, as yet unknown, manner to form an extremely gummy material that deposits on paper machine surfaces and sticks tenaciously (hence the term “Stickies”). The sticky blobs are very difficult to remove and increases machine downtime and maintenance costs as well as causing blemishes on the finished container board product Light optical image analysis, UV fluorescence, FTIR and electron microscopy are being used in consort with particle size measuring instruments, TGS and DSC thermal analysis techniques, FTIR infra-red spectroscopy as well as XRF (x-ray fluorescence spectroscopy ), XPS (x-ray photo emission spectroscopy) and classical contact angle determination methods as part of a broad program to characterize the physical and chemical nature of stickies in pulp slurries with the goal of removing them or alleviating their pronounced tendency to deposit on machinery and paper products.