The Study Of A New Fiber Loading Technology For High Ash Content Paper

To economize the source of wood fiber and reduce the production costs,using more mineral filler in the paper is the right way.But more filler used in paper affects paper performance and paper machine runability.This paper adopts the advanced experimental design method of 6 SIGMA.Fiber loading technology used in this paper is adding Ca(OH)₂ into fiber suspension,then adding CO₂ gas into the slurry,and PCC is precipitated into the inner of fiber,which is good for fiber bonding and decreases the loss of paper strengths.LBKP,APMP and BCTMP pulp were researched by this technology to improve the ash content and Z-bond of paper,solve the contradiction between ash content and filler retention.Major findings of the study were as follows:1.Design of Experiments(DOE),which can screen out the most important factor in an experiment,was used in this study.Four-factors-two-levels experiments,with pulp concentration,rotating speed,pressure of CO₂ gas and reacting time as the main factors,were desighed and studied.The results showed that rotating speed was the key factor;compared with direct loading,it can improve both paper strength(including Z-bond) and ash content,but the paper optical properties were affected.2.The fiber loading result for APMP was better than that of BCTMP.3.SEM photographs of handsheet samples showed that some of the calcium carbonate were successfully precipitated into the fiber wall and fiber lumen.4.Adding dispersant(sodium polyacrylate)before Carbonation reaction,compared with no use of dispersant,the filler retention reduced,ash content was declined and paper strength improved.However,the adding of dispersant resulted in the improvement of the optical properties of paper,because the calcium carbonate size was smaller by adding dispersant.Adding PEI before Carbonation reaction,compared with no use of PEI,resulted in reduce of ash content,improvement of paper strength properties and optical properties.5.The pulp proportion was 10 percent of fiber loaded APMP,10 percent of NBKP,and 80 percent of LBKP.Compared with direct loading in the same filling content,the dewatering property was better;it would consume 50% less filler when obtain same ash content.When the contents of adding filler were 10% and 15% in fiber loading process,compared to that of 25% in direct loading process,the paper ash content were improved by 19.27% and 36.87%,respectively;breaking length were improved by 7.18% and 1.44%,respectively;brusting strength were both improved by 4.81%;Scott were improved by 12.84% and 7.34%,respectively.Z-bond of paper made in high speed paper machine is normally low.Fiber loading is a new method to solve this problem.The improvement of paper Z-bond is also good for high-speed printing production.