IMPROVING THE SMOOTHNESS OF ALKALINE BLEACHED BOARD USING A NOVEL PRECIPITATED CALCIUM CARBONATE (PCC) FILLER

摘要

Increasing the quality of North American solid bleached sulfate board (SBS) while lowering manufacturing costs is a mostrnformidable task for any papermaker. Bleached board producers can draw upon the experience of fine-paper manufacturers,rnwho found they could improve production costs by reducing the amount of bleached fiber used through the addition ofrnmineral fillers such as precipitated calcium carbonate.rnFor a mineral filler to be effective in SBS board, a balance of bulk, stiffness, smoothness, brightness, runnability, and costrnmust be achieved to give manufacturers the ability to meet the increasing demands of a competitive paperboard market.rnWith this in mind, a novel precipitated calcium carbonate (PCC) filler has been developed which provides a balance of thesernproperties. This product improves production economics with greater filler for fiber replacement potential than any otherrnmineral filler currently available.rnMany fillers fall short in maintaining bulk and stiffness. However, this new PCC particle not only maintains bulk andrnstiffness, it also provides exceptional surface smoothness upon calendering, due to its particle shape, large size, andrnextremely low surface area. Better surface smoothness and brightness are important to improving the quality of thernsubstrate for coating applications which will allow coated SBS board to meet the increasing graphic quality demands forrnprinting and appearance.rnTo this end, a study was performed to show how the properties of paperboard could be improved by using this new PCCrnfiller. This work compared traditional acid bleached board to alkaline bleached board using various calcium carbonaternfillers under controlled conditions, focusing on calendering pressure and the impact of calendering pressure on bleachedrnboard smoothness, stiffness and other end-use properties.