Natural carbonate filler in printing paper grades
Solutions of cationic starches with degree of substitution in the range from 0,035 to 0,047 have been used for modification of ground calcium carbonate filler (chalk). Particle size distribution of modified calk estimated by using the sedimentation method as well as electrokinetic properties (ξ-potential) of chalk and printability of paper have been investigated. A key finding of this research is that the filler modification allow to particle electrokinetic charge exchanging. This opportunity positively affect on chalk retention and printability of paper incorporated therein. A Mill trial of modification of chalk with cationic starch was carried out. Mill trials confirmed that paper producing with modified filler has increasing filler content and higher printability.