Development of Mineral Hybrid Fiber from Calcium Carbonate and Pulp Using Fluid-jet Cavitation

摘要

Studies on the synthesis and characterization of a hybrid fiber (HF) consisting of precipitated calcium carbonate (PCC) and cellulose fiber were conducted. The PCC-HF has been prepared by modifying the carbon dioxide (CO2) method for PCC synthesis under high-pressure fluid-jet cavitation in hardwood bleached kraft pulp (HBKP) slurry. Scanning electron microscopy (SEM) observations of the HF showed that almost all fiber surfaces were covered with nano-size PCC particles. By using this PCC-HF as raw materials, the handsheet containing more than 50% PCC by weight with a high first-pass ash retention (greater than 80%). Unlike ordinary paper such as printing paper, the sheet showed remarkable physical properties, such as high flexibility without crumbling despite extreme high ash content. The SEM images from a cross section of the sheet containing 74% PCC revealed that a very little number of fibers embedded in PCC layer. This implied that the bonding mechanism of HF sheet was different from ordinary paper. In order to clarify the mechanism, the slurry of PCC-HF for handsheet making was separated into two fractions, long fibers and fines, by using the Dynamic Drainage Analyzer (DDA). It was found that the nano-size PCC was attached onto not only the surfaces of the long fibers but also those of fiber fines. Thus, the PCC-hybrid fiber fines contributed sheet properties and high ash retention.