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

Abstract

Studies on the synthesis and characterization of a hybrid fi ber (HF) consisting of precipitated calcium carbonate (PCC) and cellulose fi ber were conducted. The PCC-HF has been prepared by modifying the carbon dioxide (CO 2) method for PCC synthesis under high-pressure fl uid-jet cavitation in hardwood bleached kraft pulp (HBKP) slurry. Scanning electron microscopy (SEM) observations of the HF showed that almost all fi ber 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 fl exibility 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 fi bers embedded in PCC layer. This implied that the bonding mechanism of HF sheet was diff erent from ordinary paper. In order to clarify the mechanism, the slurry of PCC-HF for handsheet making was separated into two fractions, long fi bers and fi nes, 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 fi bers but also those of fi ber fi nes. Thus, the PCC-hybrid fi ber fi nes contributed sheet properties and high ash retention.

Structural analysis of CaCO3 nanoparticle/pulp fiber composites by tube flow fractionation

“…In previous papers, new procedures were developed to prepare precipitated CaCO3 nanoparticles or pulp-fiber composites using cavitation flow and ultrafine bubble methods to improve the adsorption stability of CaCO3 nanoparticles on pulp fiber surfaces (Fukuoka et al 2019;Fuchise-Fukuoka et al 2020). In this study, a precipitated CaCO3 nanoparticle or unbeaten pulp fiber slurry was separated into five fractions using TFF, and the interactions between the CaCO3 nanoparticles and long and short pulp fibers were studied from optical and SEM images, mass ratios, and the CaCO3 contents of the fractions.…”